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1.  Short- and Medium-Term Efficacy of a Web-Based Computer-Tailored Nutrition Education Intervention for Adults Including Cognitive and Environmental Feedback: Randomized Controlled Trial 
Web-based, computer-tailored nutrition education interventions can be effective in modifying self-reported dietary behaviors. Traditional computer-tailored programs primarily targeted individual cognitions (knowledge, awareness, attitude, self-efficacy). Tailoring on additional variables such as self-regulation processes and environmental-level factors (the home food environment arrangement and perception of availability and prices of healthy food products in supermarkets) may improve efficacy and effect sizes (ES) of Web-based computer-tailored nutrition education interventions.
This study evaluated the short- and medium-term efficacy and educational differences in efficacy of a cognitive and environmental feedback version of a Web-based computer-tailored nutrition education intervention on self-reported fruit, vegetable, high-energy snack, and saturated fat intake compared to generic nutrition information in the total sample and among participants who did not comply with dietary guidelines (the risk groups).
A randomized controlled trial was conducted with a basic (tailored intervention targeting individual cognition and self-regulation processes; n=456), plus (basic intervention additionally targeting environmental-level factors; n=459), and control (generic nutrition information; n=434) group. Participants were recruited from the general population and randomly assigned to a study group. Self-reported fruit, vegetable, high-energy snack, and saturated fat intake were assessed at baseline and at 1- (T1) and 4-months (T2) postintervention using online questionnaires. Linear mixed model analyses examined group differences in change over time. Educational differences were examined with group×time×education interaction terms.
In the total sample, the basic (T1: ES=–0.30; T2: ES=–0.18) and plus intervention groups (T1: ES=–0.29; T2: ES=–0.27) had larger decreases in high-energy snack intake than the control group. The basic version resulted in a larger decrease in saturated fat intake than the control intervention (T1: ES=–0.19; T2: ES=–0.17). In the risk groups, the basic version caused larger decreases in fat (T1: ES=–0.28; T2: ES=–0.28) and high-energy snack intake (T1: ES=–0.34; T2: ES=–0.20) than the control intervention. The plus version resulted in a larger increase in fruit (T1: ES=0.25; T2: ES=0.37) and a larger decrease in high-energy snack intake (T1: ES=–0.38; T2: ES=–0.32) than the control intervention. For high-energy snack intake, educational differences were found. Stratified analyses showed that the plus version was most effective for high-educated participants.
Both intervention versions were more effective in improving some of the self-reported dietary behaviors than generic nutrition information, especially in the risk groups, among both higher- and lower-educated participants. For fruit intake, only the plus version was more effective than providing generic nutrition information. Although feasible, incorporating environmental-level information is time-consuming. Therefore, the basic version may be more feasible for further implementation, although inclusion of feedback on the arrangement of the home food environment and on availability and prices may be considered for fruit and, for high-educated people, for high-energy snack intake.
Trial Registration
Netherlands Trial Registry NTR3396; (Archived by WebCite at
PMCID: PMC4319071  PMID: 25599828
cognitive feedback; environmental feedback; self-regulation; computer tailoring; nutrition education; fruit consumption; vegetable consumption; fat consumption; snack consumption
2.  Reducing Alcohol Use During Pregnancy Via Health Counseling by Midwives and Internet-Based Computer-Tailored Feedback: A Cluster Randomized Trial 
Effective interventions are needed to reduce neurobehavioral impairments in children due to maternal alcohol use during pregnancy. Currently, health-counseling interventions have shown inconsistent results to reduce prenatal alcohol use. Thus, more research using health counseling is needed to gain more knowledge about the effectiveness of this type of intervention on reducing alcohol use during pregnancy. An alternative and promising strategy is computer tailoring. However, to date, no study has shown the effectiveness of this intervention mode.
The aim was to test the effectiveness of health counseling and computer tailoring on stopping and reducing maternal alcohol use during pregnancy in a Dutch sample of pregnant women using alcohol.
A total of 60 Dutch midwifery practices, randomly assigned to 1 of 3 conditions, recruited 135 health counseling, 116 computer tailoring, and 142 usual care respondents from February to September 2011. Health-counseling respondents received counseling from their midwife according to a health-counseling protocol, which consisted of 7 steps addressed in 3 feedback sessions. Computer-tailoring respondents received usual care from their midwife and 3 computer-tailored feedback letters via the Internet. Usual care respondents received routine alcohol care from their midwife. After 3 and 6 months, we assessed the effect of the interventions on alcohol use.
Multilevel multiple logistic regression analyses showed that computer-tailoring respondents stopped using alcohol more often compared to usual care respondents 6 months after baseline (53/68, 78% vs 51/93, 55%; P=.04). Multilevel multiple linear regression analyses showed that computer-tailoring respondents (mean 0.35, SD 0.31 units per week) with average (P=.007) or lower (P<.001) alcohol use before pregnancy or with average (P=.03) or lower (P=.002) social support more strongly reduced their alcohol use 6 months after baseline compared to usual care respondents (mean 0.48, SD 0.54 units per week). Six months after baseline, 72% (62/86) of the health-counseling respondents had stopped using alcohol. This 17% difference with the usual care group was not significant.
This is the first study showing that computer tailoring can be effective to reduce alcohol use during pregnancy; health counseling did not effectively reduce alcohol use. Future researchers developing a health-counseling intervention to reduce alcohol use during pregnancy are recommended to invest more in recruitment of pregnant women and implementation by health care providers. Because pregnant women are reluctant to disclose their alcohol use to health professionals and computer tailoring preserves a person’s anonymity, this effective computer-tailoring intervention is recommended as an attractive intervention for pregnant women using alcohol.
Trial Registration
Dutch Trial Register NTR 2058; (Archived by WebCite at
PMCID: PMC4275508  PMID: 25486675
alcohol drinking; pregnancy; counseling; telemedicine; midwifery
3.  EQUIPT: protocol of a comparative effectiveness research study evaluating cross-context transferability of economic evidence on tobacco control 
BMJ Open  2014;4(11):e006945.
Tobacco smoking claims 700 000 lives every year in Europe and the cost of tobacco smoking in the EU is estimated between €98 and €130 billion annually; direct medical care costs and indirect costs such as workday losses each represent half of this amount. Policymakers all across Europe are in need of bespoke information on the economic and wider returns of investing in evidence-based tobacco control, including smoking cessation agendas. EQUIPT is designed to test the transferability of one such economic evidence base—the English Tobacco Return on Investment (ROI) tool—to other EU member states.
Methods and analysis
EQUIPT is a multicentre, interdisciplinary comparative effectiveness research study in public health. The Tobacco ROI tool already developed in England by the National Institute for Health and Care Excellence (NICE) will be adapted to meet the needs of European decision-makers, following transferability criteria. Stakeholders' needs and intention to use ROI tools in sample countries (Germany, Hungary, Spain and the Netherlands) will be analysed through interviews and surveys and complemented by secondary analysis of the contextual and other factors. Informed by this contextual analysis, the next phase will develop country-specific ROI tools in sample countries using a mix of economic modelling and Visual Basic programming. The results from the country-specific ROI models will then be compared to derive policy proposals that are transferable to other EU states, from which a centralised web tool will be developed. This will then be made available to stakeholders to cater for different decision-making contexts across Europe.
Ethics and dissemination
The Brunel University Ethics Committee and relevant authorities in each of the participating countries approved the protocol. EQUIPT has a dedicated work package on dissemination, focusing on stakeholders’ communication needs. Results will be disseminated via peer-reviewed publications, e-learning resources and policy briefs.
PMCID: PMC4244438  PMID: 25421342
return on investment; tobacco; smoking cessation; cost-effectiveness
4.  Long-term health outcomes and cost-effectiveness of a computer-tailored physical activity intervention among people aged over fifty: modelling the results of a randomized controlled trial 
BMC Public Health  2014;14(1):1099.
Physical inactivity is a significant predictor of several chronic diseases, becoming more prevalent as people age. Since the aging population increases demands on healthcare budgets, effectively stimulating physical activity (PA) against acceptable costs is of major relevance. This study provides insight into long-term health outcomes and cost-effectiveness of a tailored PA intervention among adults aged over fifty.
Intervention participants (N = 1729) received tailored advice three times within four months, targeting the psychosocial determinants of PA. The intervention was delivered in different conditions (i.e. print-delivered versus Web-based, and with or without additional information on local PA opportunities). In a clustered RCT, the effects of the different intervention conditions were compared to each other and to a control group. Effects on weekly Metabolic Equivalents (MET)-hours of PA obtained one year after the intervention started were extrapolated to long-term outcomes (5-year, 10-year and lifetime horizons) in terms of health effects and quality-adjusted life years (QALYs) and its effect on healthcare costs, using a computer simulation model. Combining the model outcomes with intervention cost estimates, this study provides insight into the long-term cost-effectiveness of the intervention. Incremental cost-effectiveness ratios (ICERs) were calculated.
For all extrapolated time horizons, the printed and the Web-based intervention resulted in decreased incidence numbers for diabetes, colon cancer, breast cancer, acute myocardial infarctions, and stroke and increased QALYs as a result of increased PA. Considering a societal Willingness-to-Pay of €20,000/QALY, on a lifetime horizon the printed (ICER = €7,500/QALY) as well as the Web-based interventions (ICER = €10,100/QALY) were cost-effective. On a 5-year time horizon, the Web-based intervention was preferred over the printed intervention. On a 10-year and lifetime horizon, the printed intervention was the preferred intervention condition, since the monetary savings of the Web-based intervention did no longer outweigh its lower effects. Adding environmental information resulted in a lower cost-effectiveness.
A tailored PA intervention in a printed delivery mode, without environmental information, has the most potential for being cost-effective in adults aged over 50.
Trial registration
The current study was registered at the Dutch Trial Register (NTR2297; April 26th 2010).
Electronic supplementary material
The online version of this article (doi:10.1186/1471-2458-14-1099) contains supplementary material, which is available to authorized users.
PMCID: PMC4221676  PMID: 25342517
Cost-effectiveness; Modelling; Quality of life; Disease incidence; Physical activity; Tailored intervention; Print-delivered; Web-based
5.  An Economic Evaluation of a Video- and Text-Based Computer-Tailored Intervention for Smoking Cessation: A Cost-Effectiveness and Cost-Utility Analysis of a Randomized Controlled Trial 
PLoS ONE  2014;9(10):e110117.
Although evidence exists for the effectiveness of web-based smoking cessation interventions, information about the cost-effectiveness of these interventions is limited.
The study investigated the cost-effectiveness and cost-utility of two web-based computer-tailored (CT) smoking cessation interventions (video- vs. text-based CT) compared to a control condition that received general text-based advice.
In a randomized controlled trial, respondents were allocated to the video-based condition (N = 670), the text-based condition (N = 708) or the control condition (N = 721). Societal costs, smoking status, and quality-adjusted life years (QALYs; EQ-5D-3L) were assessed at baseline, six-and twelve-month follow-up. The incremental costs per abstinent respondent and per QALYs gained were calculated. To account for uncertainty, bootstrapping techniques and sensitivity analyses were carried out.
No significant differences were found in the three conditions regarding demographics, baseline values of outcomes and societal costs over the three months prior to baseline. Analyses using prolonged abstinence as outcome measure indicated that from a willingness to pay of €1,500, the video-based intervention was likely to be the most cost-effective treatment, whereas from a willingness to pay of €50,400, the text-based intervention was likely to be the most cost-effective. With regard to cost-utilities, when quality of life was used as outcome measure, the control condition had the highest probability of being the most preferable treatment. Sensitivity analyses yielded comparable results.
The video-based CT smoking cessation intervention was the most cost-effective treatment for smoking abstinence after twelve months, varying the willingness to pay per abstinent respondent from €0 up to €80,000. With regard to cost-utility, the control condition seemed to be the most preferable treatment. Probably, more time will be required to assess changes in quality of life. Future studies with longer follow-up periods are needed to investigate whether cost-utility results regarding quality of life may change in the long run.
Trial Registration
Nederlands Trial Register NTR3102
PMCID: PMC4195710  PMID: 25310007
6.  A Web-based computer-tailored game to reduce binge drinking among 16 to 18 year old Dutch adolescents: development and study protocol 
BMC Public Health  2014;14(1):1054.
In the Netherlands, excessive alcohol use (e.g., binge drinking) is prevalent among adolescents. Alcohol use in general and binge drinking in particular comes with various immediate and long term health risks. Thus, reducing binge drinking among this target group is very important. This article describes a two-arm Cluster Randomized Controlled Trial (CRCT) of an intervention aimed at reducing binge drinking in this target group.
The intervention is a Web-based, computer-tailored game in which adolescents receive personalized feedback on their drinking behavior aimed at changing motivational determinants related to this behavior. The development of the game is grounded in the I-Change Model. A CRTC is conducted to test the effectiveness of the game. Adolescents are recruited through schools, and schools are randomized into the experimental condition and the control condition. The experimental condition fills in a baseline questionnaire assessing demographic variables, motivational determinants of behavior (attitude, social influences, self-efficacy, intention) and alcohol use. They are also asked to invite their parents to take part in a short parental component that focusses on setting rules and communicating about alcohol. After completing the baseline questionnaire, the experimental condition continues playing the first of three game scenarios. The primary follow-up measurement takes place after four months and a second follow-up after eight months. The control condition only fills in the baseline, four and eight month follow-up measurement and then receives access to the game (i.e., a waiting list control condition). The effectiveness of the intervention to reduce binge drinking in the previous 30 days and alcohol use in the last week will be assessed. Furthermore, intention to drink and binge drink are assessed. Besides main effects, potential subgroup differences pertaining to gender, age, and educational background are explored.
The study described in this article gives insight into the effectiveness of a possible solution for a prominent public health issue in the Netherlands, which is binge drinking among 16 to 18 year old adolescents.
Trial registration
Dutch Trial Register (NTR4048). Trial registered on 06/26/2013.
PMCID: PMC4210522  PMID: 25301695
Alcohol use; Binge drinking; Adolescents; Web-based interventions; Computer-tailoring; e-Health; I-Change model
7.  Cost-effectiveness and cost-utility of a Web-based or print-delivered tailored intervention to promote physical activity among adults aged over fifty: an economic evaluation of the Active Plus intervention 
The adverse health effects of insufficient physical activity (PA) result in high costs to society. The economic burden of insufficient PA, which increases in our aging population, stresses the urgency for cost-effective interventions to promote PA among older adults. The current study provides insight in the cost-effectiveness and cost-utility of different versions of a tailored PA intervention (Active Plus) among adults aged over fifty.
The intervention conditions (i.e. print-delivered basic (PB; N = 439), print-delivered environmental (PE; N = 435), Web-based basic (WB; N = 423), Web-based environmental (WE; N = 432)) and a waiting-list control group were studied in a clustered randomized controlled trial. Intervention costs were registered during the trial. Health care costs, participant costs and productivity losses were identified and compared with the intervention effects on PA (in MET-hours per week) and quality-adjusted life years (QALYs) 12 months after the start of the intervention. Cost-effectiveness ratios (ICERs) and cost-utility ratios (ICURs) were calculated per intervention condition. Non-parametric bootstrapping techniques and sensitivity analyses were performed to account for uncertainty.
As a whole (i.e. the four intervention conditions together) the Active Plus intervention was found to be cost-effective. The PB-intervention (ICER = €-55/MET-hour), PE-intervention (ICER = €-94/MET-hour) and the WE-intervention (ICER = €-139/MET-hour) all resulted in higher effects on PA and lower societal costs than the control group. With regard to QALYs, the PB-intervention (ICUR = €38,120/QALY), the PE-intervention (ICUR = €405,892/QALY) and the WE-intervention (ICUR = €-47,293/QALY) were found to be cost-effective when considering a willingness-to-pay threshold of €20,000/QALY. In most cases PE had the highest probability to be cost-effective.
The Active Plus intervention was found to be a cost-effective manner to increase PA in a population aged over fifty when compared to no-intervention. The tailored Active Plus intervention delivered through printed material and with additional environmental information (PE) turned out to be the most cost-effective intervention condition as confirmed by the different sensitivity analyses. By increasing PA at relatively low costs, the Active Plus intervention can contribute to a better public health.
Trial registration
Dutch Trial Register: NTR2297
Electronic supplementary material
The online version of this article (doi:10.1186/s12966-014-0122-z) contains supplementary material, which is available to authorized users.
PMCID: PMC4189727  PMID: 25262435
Tailored intervention; Older adults; Physical activity; Cost-effectiveness; Cost-utility; Quality of life
8.  Predicting fruit consumption: the role of habits, previous behavior and mediation effects 
BMC Public Health  2014;14:730.
This study assessed the role of habits and previous behavior in predicting fruit consumption as well as their additional predictive contribution besides socio-demographic and motivational factors. In the literature, habits are proposed as a stable construct that needs to be controlled for in longitudinal analyses that predict behavior. The aim of this study is to provide empirical evidence for the inclusion of either previous behavior or habits.
A random sample of 806 Dutch adults (>18 years) was invited by an online survey panel of a private research company to participate in an online study on fruit consumption. A longitudinal design (N = 574) was used with assessments at baseline and after one (T2) and two months (T3). Multivariate linear regression analysis was used to assess the differential value of habit and previous behavior in the prediction of fruit consumption.
Eighty percent of habit strength could be explained by habit strength one month earlier, and 64% of fruit consumption could be explained by fruit consumption one month earlier. Regression analyses revealed that the model with motivational constructs explained 41% of the behavioral variance at T2 and 38% at T3. The addition of previous behavior and habit increased the explained variance up to 66% at T2 and to 59% at T3. Inclusion of these factors resulted in non-significant contributions of the motivational constructs. Furthermore, our findings showed that the effect of habit strength on future behavior was to a large extent mediated by previous behavior.
Both habit and previous behavior are important as predictors of future behavior, and as educational objectives for behavior change programs. Our results revealed less stability for the constructs over time than expected. Habit strength was to a large extent mediated by previous behavior and our results do not strongly suggest a need for the inclusion of both constructs. Future research needs to assess the conditions that determine direct influences of both previous behavior and habit, since these influences may differ per type of health behavior, per context stability in which the behavior is performed, and per time frame used for predicting future behavior.
PMCID: PMC4223379  PMID: 25037859
Fruit consumption; Habit; Previous behavior; SRHI
9.  Socioeconomic and country variations in cross-border cigarette purchasing as tobacco tax avoidance strategy. Findings from the ITC Europe Surveys 
Tobacco control  2013;23(0 1):i30-i38.
Legal tobacco tax avoidance strategies such as cross-border cigarette purchasing may attenuate the impact of tax increases on tobacco consumption. Little is known about socioeconomic and country variations in cross-border purchasing.
To describe socioeconomic and country variations in cross-border cigarette purchasing in six European countries.
Cross-sectional data from adult smokers (n = 7,873) from the International Tobacco Control (ITC) Surveys in France (2006/7), Germany (2007), Ireland (2006), the Netherlands (2008), Scotland (2006), and the rest of the United Kingdom (2007/8) were used. Respondents were asked whether they had bought cigarettes outside their country in the last six months and how often.
In French and German provinces/states bordering countries with lower cigarette prices, 24% and 13% of smokers respectively reported purchasing cigarettes frequently outside their country. In non-border regions of France and Germany and in Ireland, Scotland, the rest of the United Kingdom, and the Netherlands, frequent purchasing of cigarettes outside the country was reported by 2% to 7% of smokers. Smokers with higher levels of education or income, younger smokers, daily smokers, heavier smokers, and smokers not planning to quit smoking were more likely to purchase cigarettes outside their country.
Cross-border cigarette purchasing is more common in European regions bordering countries with lower cigarette prices and is more often reported by smokers with higher education and income. Increasing taxes in countries with lower cigarette prices and reducing the number of cigarettes that can be legally imported across borders could help to avoid cross-border purchasing.
PMCID: PMC4009359  PMID: 23644287
Europe; tobacco tax; cross-border purchasing; social class
10.  Adolescents’ Beliefs About Forced Sex in KwaZulu-Natal, South Africa 
Archives of Sexual Behavior  2014;43(6):1087-1095.
Gender-based violence has serious consequences for the psychological, physical, and sexual well-being of both men and women. Various gender roles, attitudes, and practices in South Africa create an environment that fosters submission and silence in females and hegemony and coercion in males. One of the expressions of this power inequity is a high prevalence of forced sex, which in its turn is associated with higher risk of HIV infection. This study therefore assessed potential gender differences in beliefs about forced sex and in prevalence of reported forced sex among high school students (N = 764) in KwaZulu-Natal. Results showed that significantly more boys were sexually active (26 %) than girls (12 %) and that boys experienced earlier sexual debut by over a year. Boys also held a more positive view about forced sex than girls since they associated it more often with signs of love, as an appropriate way to satisfy sexual urges, and as acceptable if the girl was financially dependent on the boy. The perception that peers and friends considered forced sex to be an effective way to punish a female partner was also more common among boys. On the other hand, boys were less knowledgeable about the health and legal consequences of forced sex, but no significant differences were found for other sociocognitive items, such as self-efficacy and behavioral intention items. Consequently, health education programs are needed to inform both boys and girls about the risks of forced sex, to convince boys and their friends about its inappropriateness and girls to empower themselves to avoid forced sex.
PMCID: PMC4133072  PMID: 24729133
Gender; Sex differences; Forced sex; Rape; Self-efficacy; Social norms; South Africa
11.  Efficacy of a Web-Based Computer-Tailored Smoking Prevention Intervention for Dutch Adolescents: Randomized Controlled Trial 
Preventing smoking initiation among adolescents is crucial to reducing tobacco-caused death and disease. This study focuses on the effectiveness of a Web-based computer-tailored smoking prevention intervention aimed at adolescents.
The intent of the study was to describe the intervention characteristics and to show the effectiveness and results of a randomized controlled trial. We hypothesized that the intervention would prevent smoking initiation among Dutch secondary school students aged 10-20 years and would have the largest smoking prevention effect among the age cohort of 14-16 years, as smoking uptake in that period is highest.
The intervention consisted of a questionnaire and fully automated computer-tailored feedback on intention to start smoking and motivational determinants. A total of 89 secondary schools were recruited via postal mail and randomized into either the computer-tailored intervention condition or the control condition. Participants had to complete a Web-based questionnaire at baseline and at 6-month follow-up. Data on smoking initiation were collected from 897 students from these schools. To identify intervention effects, multilevel logistic regression analyses were conducted using multiple imputation.
Smoking initiation among students aged 10-20 years was borderline significantly lower in the experimental condition as compared to the control condition 6 months after baseline (OR 0.25, 95% CI 0.05-1.21, P=.09). Additional analyses of the data for the 14-16 year age group showed a significant effect, with 11.5% (24/209) of the students in the control condition reporting initiation compared to 5.7% (10/176) in the experimental condition (OR 0.22, 95% CI 0.05-1.02, P=.05). No moderation effects were found regarding gender and educational level.
The findings of this study suggest that computer-tailored smoking prevention programs are a promising way of preventing smoking initiation among adolescents for at least 6 months, in particular among the age cohort of 14-16 years. Further research is needed to focus on long-term effects.
Trial Registration
International Standard Randomized Controlled Trial Number (ISRCTN): 77864351; (Archived by WebCite at
PMCID: PMC3978560  PMID: 24657434
computer tailoring; Web-based intervention; Internet; smoking prevention; smoking initiation; adolescents; randomized controlled trial
12.  Economic Evaluation of a Web-Based Tailored Lifestyle Intervention for Adults: Findings Regarding Cost-Effectiveness and Cost-Utility From a Randomized Controlled Trial 
Different studies have reported the effectiveness of Web-based computer-tailored lifestyle interventions, but economic evaluations of these interventions are scarce.
The objective was to assess the cost-effectiveness and cost-utility of a sequential and a simultaneous Web-based computer-tailored lifestyle intervention for adults compared to a control group.
The economic evaluation, conducted from a societal perspective, was part of a 2-year randomized controlled trial including 3 study groups. All groups received personalized health risk appraisals based on the guidelines for physical activity, fruit intake, vegetable intake, alcohol consumption, and smoking. Additionally, respondents in the sequential condition received personal advice about one lifestyle behavior in the first year and a second behavior in the second year; respondents in the simultaneous condition received personal advice about all unhealthy behaviors in both years. During a period of 24 months, health care use, medication use, absenteeism from work, and quality of life (EQ-5D-3L) were assessed every 3 months using Web-based questionnaires. Demographics were assessed at baseline, and lifestyle behaviors were assessed at both baseline and after 24 months. Cost-effectiveness and cost-utility analyses were performed based on the outcome measures lifestyle factor (the number of guidelines respondents adhered to) and quality of life, respectively. We accounted for uncertainty by using bootstrapping techniques and sensitivity analyses.
A total of 1733 respondents were included in the analyses. From a willingness to pay of €4594 per additional guideline met, the sequential intervention (n=552) was likely to be the most cost-effective, whereas from a willingness to pay of €10,850, the simultaneous intervention (n=517) was likely to be most cost-effective. The control condition (n=664) appeared to be preferred with regard to quality of life.
Both the sequential and the simultaneous lifestyle interventions were likely to be cost-effective when it concerned the lifestyle factor, whereas the control condition was when it concerned quality of life. However, there is no accepted cutoff point for the willingness to pay per gain in lifestyle behaviors, making it impossible to draw firm conclusions. Further economic evaluations of lifestyle interventions are needed.
Trial Registration
Dutch Trial Register NTR2168; (Archived by WebCite at
PMCID: PMC3978559  PMID: 24650860
randomized controlled trial; economic evaluation; cost-effectiveness; cost-utility; lifestyle behaviors; Internet interventions; Web-based; computer-tailoring
13.  Do Email and Mobile Phone Prompts Stimulate Primary School Children to Reuse an Internet-Delivered Smoking Prevention Intervention? 
Improving the use (eg, initial visit and revisits) of Internet-delivered interventions to promote healthy lifestyles such as non-smoking is one of the largest challenges in the field of eHealth. Prompts have shown to be effective in stimulating reuse of Internet-delivered interventions among adults and adolescents. However, evidence concerning effectiveness of prompts to promote reuse of a website among children is still scarce.
The aim of this study is to investigate (1) whether prompts are effective in promoting reuse of an intervention website containing information on smoking prevention for children, (2) whether the content of the prompt is associated with its effect in terms of reuse, and (3) whether there are differences between children who do or do not respond to prompts.
The sample of this cluster-randomized study consisted of 1124 children (aged 10-11 years) from 108 Dutch primary schools, who were assigned to the experimental group of an Internet-delivered smoking prevention intervention study. All participants completed a Web-based questionnaire on factors related to (non-)smoking. Schools were randomized to a no-prompt group (n=50) or a prompt group (n=58). All children could revisit the intervention website, but only the children in the prompt group received email and SMS prompts to revisit the website. Those prompt messages functioned as a teaser to stimulate reuse of the intervention website. Reuse of the website was objectively tracked by means of a server registration system. Repeated measures analysis of variance and linear regression analysis were performed to assess the effects of prompts on website reuse and to identify individual characteristics of participants who reuse the intervention website.
Children in the prompt group reused the intervention website significantly more often compared to children in the no-prompt group (B=1.56, P<.001). Prompts announcing new animated videos (F 1,1122=9.33, P=.002) and games about (non-)smoking on the website (F 1,1122=8.28, P=.004) resulted in most reuse of the website. Within the prompt group, children with a low socioeconomic status (SES) reused the intervention website more often (B=2.19, P<.001) than children of high SES (B=0.93, P=.005).
Prompts can stimulate children to reuse an intervention website aimed at smoking prevention. Prompts showed, furthermore, to stimulate children of a low SES slightly more to reuse an intervention website, which is often a difficult target group in terms of stimulating participation. However, the number of revisits was quite low, which requires further study into how prompts can be optimized in terms of content and frequency to improve the number of revisits.
Trial Registration
Netherlands Trial Register Number: NTR3116; (Archived by WebCite at
PMCID: PMC3978553  PMID: 24642082
Internet; Internet-delivered intervention; prompts; primary school children; computer-tailoring
14.  Comparison of Text and Video Computer-Tailored Interventions for Smoking Cessation: Randomized Controlled Trial 
A wide range of effective smoking cessation interventions have been developed to help smokers to quit. Smoking rates remain high, especially among people with a lower level of education. Multiple tailoring adapted to the individual’s readiness to quit and the use of visual messaging may increase smoking cessation.
The results of video and text computer tailoring were compared with the results of a control condition. Main effects and differential effects for subgroups with different educational levels and different levels of readiness to quit were assessed.
During a blind randomized controlled trial, smokers willing to quit within 6 months were assigned to a video computer tailoring group with video messages (n=670), a text computer tailoring group with text messages (n=708), or to a control condition with short generic text advice (n=721). After 6 months, effects on 7-day point prevalence abstinence and prolonged abstinence were assessed using logistic regression analyses. Analyses were conducted in 2 samples: (1) respondents (as randomly assigned) who filled in the baseline questionnaire and completed the first session of the program, and (2) a subsample of sample 1, excluding respondents who did not adhere to at least one further intervention session. In primary analyses, we used a negative scenario in which respondents lost to follow-up were classified as smokers. Complete case analysis and multiple imputation analyses were considered as secondary analyses.
In sample 1, the negative scenario analyses revealed that video computer tailoring was more effective in increasing 7-day point prevalence abstinence than the control condition (OR 1.45, 95% CI 1.09-1.94, P=.01). Video computer tailoring also resulted in significantly higher prolonged abstinence rates than controls among smokers with a low (ready to quit within 4-6 months) readiness to quit (OR 5.13, 95% CI 1.76-14.92, P=.003). Analyses of sample 2 showed similar results, although text computer tailoring was also more effective than control in realizing 7-day point prevalence abstinence. No differential effects were found for level of education. Complete case analyses and multiple imputation yielded similar results.
In all analyses, video computer tailoring was effective in realizing smoking cessation. Furthermore, video computer tailoring was especially successful for smokers with a low readiness to quit smoking. Text computer tailoring was only effective for sample 2. Results suggest that video-based messages with personalized feedback adapted to the smoker’s motivation to quit might be effective in increasing abstinence rates for smokers with diverse educational levels.
Trial Registration
Netherlands Trial Register: NTR3102; (Archived by WebCite at
PMCID: PMC3961744  PMID: 24589938
smoking cessation; multiple computer tailoring; delivery strategy; educational level; text messages; video messages
15.  Explaining socio-economic differences in intention to smoke among primary school children 
BMC Public Health  2014;14:191.
Smoking prevalence is higher among low socio-economic status (LSES) groups, and this difference may originate from a higher intention to smoke in childhood. This study aims to identify factors that explain differences in intention to smoke between children living in high socio-economic status (HSES) and LSES neighbourhoods.
Cross-sectional data were derived from the baseline assessment of a smoking prevention intervention study. Dutch primary school children, aged 10 – 11 years (N = 2,612), completed a web-based questionnaire about their attitude, subjective norm, self-efficacy expectations, modelling and intention to smoke. Linear and logistic regression analyses were performed to assess potential individual cognitive (attitude, subjective norm and self-efficacy) and social environmental (modelling) mediators between SES and intention to smoke.
Multiple mediation models indicated that modelling mediated the association between SES (B = -0.09 (p < 0.01)) and intention to smoke (B = 1.06 (p < 0.01)). Mainly the father, mother and other family members mediated this association. Gender did not moderate the association between SES and intention to smoke and the potential mediators indicating that there are no differences in mediating factors between boys and girls.
This study indicates that future smoking prevention studies may focus on the social environment to prevent smoking onset. However, replication of this study is warranted.
Trial registration
This study was approved by the Medical Ethics Committee of the Atrium-Orbis-Zuyd Hospital (NL32093.096.11 / MEC 11-T-25) and registered in the Dutch Trial Register (NTR3116).
PMCID: PMC3938073  PMID: 24555819
Socio-economic status; Intention to smoke; Primary school; Mediation analyses
16.  Correlates of the Intention to Implement a Tailored Physical Activity Intervention: Perceptions of Intermediaries 
The public health impact of health behaviour interventions is highly dependent on large-scale implementation. Intermediaries—intervention providers—determine to a large extent whether an intervention reaches the target population, and hence its impact on public health. A cross-sectional study was performed to identify the correlates of intermediaries’ intention to implement a computer-tailored physical activity intervention. According to theory, potential correlates are intervention characteristics, organisational characteristics, socio-political characteristics and intermediary characteristics. This study investigated whether intermediary characteristics mediated the association between the intervention, organisational and socio-political characteristics and intention to implement the intervention. Results showed that intervention characteristics (i.e., observability (B = 0.53; p = 0.006); relative advantage (B = 0.79; p = 0.020); complexity (B = 0.80; p < 0.001); compatibility (B = 0.70; p < 0.001)), organisational characteristics (i.e., type of organization (B = 0.38; p = 0.002); perceived task responsibility (B = 0.66; p ≤ 0.001); capacity (B = 0.83; p < 0.001)), and the social support received by intermediary organisations (B = 0.81; p < 0.001) were associated with intention to implement the intervention. These factors should thus be targeted by an implementation strategy. Since self-efficacy and social norms perceived by the intermediary organisations partially mediated the effects of other variables on intention to implement the intervention (varying between 29% and 84%), these factors should be targeted to optimise the effectiveness of the implementation strategy.
PMCID: PMC3945575  PMID: 24518647
intervention implementation; hypothesized determinants of implementation intention; tailored intervention; intervention characteristics; organisational characteristics; socio-political characteristics; intermediary characteristics
17.  Effects of a Web-Based Tailored Multiple-Lifestyle Intervention for Adults: A Two-Year Randomized Controlled Trial Comparing Sequential and Simultaneous Delivery Modes 
Web-based computer-tailored interventions for multiple health behaviors can have a significant public health impact. Yet, few randomized controlled trials have tested this assumption.
The objective of this paper was to test the effects of a sequential and simultaneous Web-based tailored intervention on multiple lifestyle behaviors.
A randomized controlled trial was conducted with 3 tailoring conditions (ie, sequential, simultaneous, and control conditions) in the Netherlands in 2009-2012. Follow-up measurements took place after 12 and 24 months. The intervention content was based on the I-Change model. In a health risk appraisal, all respondents (N=5055) received feedback on their lifestyle behaviors that indicated whether they complied with the Dutch guidelines for physical activity, vegetable consumption, fruit consumption, alcohol intake, and smoking. Participants in the sequential (n=1736) and simultaneous (n=1638) conditions received tailored motivational feedback to change unhealthy behaviors one at a time (sequential) or all at the same time (simultaneous). Mixed model analyses were performed as primary analyses; regression analyses were done as sensitivity analyses. An overall risk score was used as outcome measure, then effects on the 5 individual lifestyle behaviors were assessed and a process evaluation was performed regarding exposure to and appreciation of the intervention.
Both tailoring strategies were associated with small self-reported behavioral changes. The sequential condition had the most significant effects compared to the control condition after 12 months (T1, effect size=0.28). After 24 months (T2), the simultaneous condition was most effective (effect size=0.18). All 5 individual lifestyle behaviors changed over time, but few effects differed significantly between the conditions. At both follow-ups, the sequential condition had significant changes in smoking abstinence compared to the simultaneous condition (T1 effect size=0.31; T2 effect size=0.41). The sequential condition was more effective in decreasing alcohol consumption than the control condition at 24 months (effect size=0.27). Change was predicted by the amount of exposure to the intervention (total visiting time: beta=–.06; P=.01; total number of visits: beta=–.11; P<.001). Both interventions were appreciated well by respondents without significant differences between conditions.
Although evidence was found for the effectiveness of both programs, no simple conclusive finding could be drawn about which intervention mode was more effective. The best kind of intervention may depend on the behavior that is targeted or on personal preferences and motivation. Further research is needed to identify moderators of intervention effectiveness. The results need to be interpreted in view of the high and selective dropout rates, multiple comparisons, and modest effect sizes. However, a large number of people were reached at low cost and behavioral change was achieved after 2 years.
Trial Registration
Nederlands Trial Register: NTR 2168; (Archived by WebCite at
PMCID: PMC3936298  PMID: 24472854
multiple behavior change; Web-based intervention; computer tailoring; effectiveness; physical activity; fruit consumption; vegetable consumption; alcohol intake; smoking
18.  Promoting sexual and reproductive health among adolescents in southern and eastern Africa (PREPARE): project design and conceptual framework 
BMC Public Health  2014;14:54.
Young people in sub-Saharan Africa are affected by the HIV pandemic to a greater extent than young people elsewhere and effective HIV-preventive intervention programmes are urgently needed. The present article presents the rationale behind an EU-funded research project (PREPARE) examining effects of community-based (school delivered) interventions conducted in four sites in sub-Saharan Africa. One intervention focuses on changing beliefs and cognitions related to sexual practices (Mankweng, Limpopo, South Africa). Another promotes improved parent-offspring communication on sexuality (Kampala, Uganda). Two further interventions are more comprehensive aiming to promote healthy sexual practices. One of these (Western Cape, South Africa) also aims to reduce intimate partner violence while the other (Dar es Salaam, Tanzania) utilises school-based peer education.
A modified Intervention Mapping approach is used to develop all programmes. Cluster randomised controlled trials of programmes delivered to school students aged 12–14 will be conducted in each study site. Schools will be randomly allocated (after matching or stratification) to intervention and delayed intervention arms. Baseline surveys at each site are followed by interventions and then by one (Kampala and Limpopo) or two (Western Cape and Dar es Salaam) post-intervention data collections. Questionnaires include questions common for all sites and are partly based on a set of social cognition models previously applied to the study of HIV-preventive behaviours. Data from all sites will be merged in order to compare prevalence and associations across sites on core variables. Power is set to .80 or higher and significance level to .05 or lower in order to detect intervention effects. Intraclass correlations will be estimated from previous surveys carried out at each site.
We expect PREPARE interventions to have an impact on hypothesized determinants of risky sexual behaviour and in Western Cape and Dar es Salaam to change sexual practices. Results from PREPARE will (i) identify modifiable cognitions and social processes related to risky sexual behaviour and (ii) identify promising intervention approaches among young adolescents in sub-Saharan cultures and contexts.
Trial registrations
Controlled Trials ISRCTN56270821 (Cape Town); Controlled Trials ISRCTN10386599 (Limpopo); Clinical Trials NCT01772628 (Kampala); Australian New Zealand Clinical Trials Registry ACTRN12613000900718 (Dar es Salaam).
PMCID: PMC3908968  PMID: 24438582
19.  Integrating a tailored e-health self-management application for chronic obstructive pulmonary disease patients into primary care: a pilot study 
BMC Family Practice  2014;15:4.
Changes in reimbursement have been compelling for Dutch primary care practices to apply a disease management approach for patients with chronic obstructive pulmonary disease (COPD). This approach includes individual patient consultations with a practice nurse, who coaches patients in COPD management. The aim of this study was to gauge the feasibility of adding a web-based patient self-management support application, by assessing patients’ self-management, patients’ health status, the impact on the organization of care, and the level of application use and appreciation.
The study employed a mixed methods design. Six practice nurses recruited COPD patients during a consultation. The e-Health application included a questionnaire that captured information on demographics, self-management related behaviors (smoking cessation, physical activity and medication adherence) and their determinants, and nurse recommendations. The application provided tailored feedback messages to patients and provided the nurse with reports. Data were collected through questionnaires and medical record abstractions at baseline and one year later. Semi-structured interviews with patients and nurses were conducted. Descriptive statistics were calculated for quantitative data and content analysis was used to analyze the qualitative data.
Eleven patients, recruited by three nurses, used the application 1 to 7 times (median 4). Most patients thought that the application supported self-management, but their interest diminished after multiple uses. Impact on patients’ health could not be determined due to the small sample size. Nurses reported benefits for the organization of care and made suggestions to optimize the use of the reports.
Results suggest that it is possible to integrate a web-based COPD self-management application into the current primary care disease management process. The pilot study also revealed opportunities to improve the application and reports, in order to increase technology use and appreciation.
PMCID: PMC3907149  PMID: 24400676
Chronic obstructive pulmonary disease; e-Health intervention; Tailoring; Self-management; Smoking cessation; Physical activity; Medication adherence; Primary care
20.  Which factors play a role in Dutch health promotion professionals’ decision to recruit actively primary schools to use a web-based smoking prevention programme? 
BMC Research Notes  2013;6:504.
Municipal Health Promotion Organisations (MHPOs) play an important role in promoting and disseminating prevention programmes, such as smoking prevention programmes, in schools. This study identifies factors that may facilitate or hinder MHPOs’ willingness to recruit actively primary schools to use a smoking prevention programme.
In 2011, 31 Dutch MHPOs were invited to recruit schools to use a smoking prevention programme. All MHPO employees involved in smoking prevention activities (n = 68) were asked to complete a questionnaire assessing psychological factors and characteristics of their organisation that might affect their decision to be involved in active recruitment of schools. T-tests and multivariate analysis of variance assessed potential differences in psychological and organisational factors between active and non-active recruiters.
A total of 45 professionals returned the questionnaire (66.2%). Active recruiters (n = 12) had more positive attitudes (p = 0.02), higher self-efficacy expectations (p < 0.01) and formulated more plans (p < 0.01) to recruit primary schools, compared with non-active recruiters. Organisational factors did not discriminate between active and non-active recruiters.
Primarily psychological factors seem to be associated with MHPOs’ decision to recruit schools actively. This indicates that creating more positive attitude, self-efficacy beliefs and formation of plans may help in getting more MHPOs involved in active recruitment procedures.
PMCID: PMC4222116  PMID: 24298942
Recruitment; Decision-making; Smoking prevention; Primary school
21.  Pathways of Change Explaining the Effect of Smoke-Free Legislation on Smoking Cessation in the Netherlands. An Application of the International Tobacco Control Conceptual Model 
Nicotine & Tobacco Research  2012;14(12):1474-1482.
This study aims to test the pathways of change from individual exposure to smoke-free legislation on smoking cessation, as hypothesized in the International Tobacco Control (ITC) Conceptual Model.
A nationally representative sample of Dutch smokers aged 15 years and older was surveyed during 4 consecutive annual surveys. Of the 1,820 baseline smokers, 1,012 participated in the fourth survey. Structural Equation Modeling was employed to test a model of the effects of individual exposure to smoke-free legislation through policy-specific variables (support for smoke-free legislation and awareness of the harm of [secondhand] smoking) and psychosocial mediators (attitudes, subjective norm, self-efficacy, and intention to quit) on quit attempts and quit success.
The effect of individual exposure to smoke-free legislation on smoking cessation was mediated by 1 pathway via support for smoke-free legislation, attitudes about quitting, and intention to quit smoking. Exposure to smoke-free legislation also influenced awareness of the harm of (secondhand) smoking, which in turn influenced the subjective norm about quitting. However, only attitudes about quitting were significantly associated with intention to quit smoking, whereas subjective norm and self-efficacy for quitting were not. Intention to quit predicted quit attempts and quit success, and self-efficacy for quitting predicted quit success.
Our findings support the ITC Conceptual Model, which hypothesized that policies influence smoking cessation through policy-specific variables and psychosocial mediators. Smoke-free legislation may increase smoking cessation, provided that it succeeds in influencing support for the legislation.
PMCID: PMC3509014  PMID: 22491892
22.  Designing a theory- and evidence-based tailored eHealth rehabilitation aftercare program in Germany and the Netherlands: study protocol 
BMC Public Health  2013;13:1081.
Cardiac rehabilitation programs aim to improve health status and to decrease the risk of further cardiac events. Persons undergoing rehabilitation often have difficulties transferring the learned health behaviors into their daily routine after returning home and maybe to work. This includes physical activity as well as fruit and vegetable consumption. Computer-based tailored interventions have been shown to be effective in increasing physical activity as well as fruit and vegetable consumption. The aim of this study is, to support people in transferring these two learned behavior changes and their antecedents into their daily life after cardiac rehabilitation.
The study will have a randomized controlled design and will be conducted among German and Dutch people who participated in cardiac rehabilitation. The study will consist of one intervention group which will be compared to a waiting list control group. During the eight week duration of the intervention, participants will be invited to participate in the online after-care program once per week. The intervention encourages participants to define individual health behavior goals as well as action, and coping plans to reach these self-determined goals. The effectiveness of the program will be compared between the intervention condition and the control group in terms of behavior change, antecedents of behavior change (e.g., self-efficacy), ability to return to work and increased well-being. Further, subgroup-differences will be assessed including differences between the two countries, socioeconomic inequalities and across age groups.
The present study will make a contribution to understanding how such an online-based tailored interventions enables study participants to adopt and maintain a healthy lifestyle. Implications can include how such an online program could enrich cardiac rehabilitation aftercare further.
Trial registration
NTR 3706, NCT01909349
PMCID: PMC3840618  PMID: 24245493
Cardiac rehabilitation aftercare; Physical exercise; Fruit and vegetable consumption; Multiple behavior changes; Internet based intervention; Tailored feedback; Cardiovascular diseases
23.  Systematic development of a text-driven and a video-driven web-based computer-tailored obesity prevention intervention 
BMC Public Health  2013;13:978.
This paper describes the systematic development of a text-driven and a video-driven web-based computer-tailored intervention aimed to prevent obesity among normal weight and overweight adults. We hypothesize that the video-driven intervention will be more effective and appealing for individuals with a low level of education.
Methods and Design
The Intervention Mapping protocol was used to develop the interventions, which have exactly the same educational content but differ in the format in which the information is delivered. One intervention is fully text-based, while in the other intervention in addition to text-based feedback, the core messages are provided by means of videos. The aim of the interventions is to prevent weight gain or achieve modest weight loss by making small changes in dietary intake or physical activity. The content of the interventions is based on the I-Change Model and self-regulation theories and includes behavior change methods such as consciousness raising, tailored feedback on behavior and cognitions, goal setting, action and coping planning, and evaluation of goal pursuit. The interventions consist of six sessions. In the first two sessions, participants will set weight and behavioral change goals and form plans for specific actions to achieve the desired goals. In the remaining four sessions, participants’ will evaluate their progress toward achievement of the behavioral and weight goals. They will also receive personalized feedback on how to deal with difficulties they may encounter, including the opportunity to make coping plans and the possibility to learn from experiences of others. The efficacy and appreciation of the interventions will be examined by means of a three-group randomized controlled trial using a waiting list control group. Measurements will take place at baseline and six and twelve months after baseline. Primary outcome measures are body mass index, physical activity, and dietary intake.
The present paper provides insight into how web-based computer-tailored obesity prevention interventions consisting of self-regulation concepts and text-driven and video-driven messages can be developed systematically. The evaluation of the interventions will provide insight into their efficacy and will result in recommendations for future web-based computer-tailored interventions and the additional value of using video tailoring.
Trial registration
PMCID: PMC4015713  PMID: 24138937
Obesity; Physical activity; Diet; Intervention mapping protocol; Computer-tailoring; Weight management; Education level
24.  Determinants of binge drinking in a permissive environment: focus group interviews with Dutch adolescents and parents 
BMC Public Health  2013;13:882.
Compared to other European countries, the Netherlands score among the highest of binge drinking rates of 16 to 18 year old adolescents. Dutch adolescents aged 16 are legally allowed to buy and consume low strength alcoholic beverages. This study focused on determinants of binge drinking in such a permissive environment from the perspectives of adolescents and parents.
Focus group interviews were conducted with adolescents aged 16 to 18 (N = 83), and parents of adolescents from this age group (N = 24). Data was analysed using thematic analyses methods.
Most reasons adolescents mentioned for drinking were to relax, increase a good mood and to be social. Also peers around them influenced and increased adolescents’ drinking. Comparing adolescents and parental statements about their perspectives how alcohol use is handled and accepted by the parents we found that generally, those perspectives match. Parents as well as adolescents stated that alcohol use is accepted by parents. However, when looking at essential details, like the acceptable amounts that children may consume, the perspectives differ enormously. Adolescents think their parents accept any amount of drinking as long as they do not get drunk, whereas parents reported acceptable limits of 1 or 2 glasses every two weeks. Parents further indicated that they felt unsupported by the Dutch policies and regulations of alcohol use. Most of them were in favour of an increase of the legal purchasing age to 18 years.
Parents and adolescents should both be targeted in interventions to reduce alcohol use among adolescents. In particular, communication between parents and children should be improved, in order to avoid misconceptions about acceptable alcohol use. Further, adolescents should be supported to handle difficult social situations with peers where they feel obliged to drink. Additionally, revisions of policies towards a less permissive standpoint are advised to support parents and to impede availability of alcoholic beverages for adolescents/children younger than 18 years.
PMCID: PMC3852358  PMID: 24063544
Alcohol; Adolescents; Binge drinking; Focus group interviews; Parents
25.  Effects of a Web-Based Tailored Intervention to Reduce Alcohol Consumption in Adults: Randomized Controlled Trial 
Web-based tailored interventions provide users with information that is adapted to their individual characteristics and needs. Randomized controlled trials assessing the effects of tailored alcohol self-help programs among adults are scarce. Furthermore, it is a challenge to develop programs that can hold respondents’ attention in online interventions.
To assess whether a 3-session, Web-based tailored intervention is effective in reducing alcohol intake in high-risk adult drinkers and to compare 2 computer-tailoring feedback strategies (alternating vs summative) on behavioral change, dropout, and appreciation of the program.
A single-blind randomized controlled trial was conducted with an experimental group and a control group (N=448) in Germany in 2010-2011. Follow-up took place after 6 months. Drinking behavior, health status, motivational determinants, and demographics were assessed among participants recruited via an online access panel. The experimental group was divided into 2 subgroups. In the alternating condition (n=132), the tailored feedback was split into a series of messages discussing individual topics offered while the respondent was filling out the program. Participants in the summative condition (n=181) received all advice at once after having answered all questions. The actual texts were identical for both conditions. The control group (n=135) only filled in 3 questionnaires. To identify intervention effects, logistic and linear regression analyses were conducted among complete cases (n=197) and after using multiple imputation.
Among the complete cases (response rate: 197/448, 44.0%) who did not comply with the German national guideline for low-risk drinking at baseline, 21.1% of respondents in the experimental group complied after 6 months compared with 5.8% in the control group (effect size=0.42; OR 2.65, 95% CI 1.14-6.16, P=.02). The experimental group decreased by 3.9 drinks per week compared to 0.4 drinks per week in the control group, but this did not reach statistical significance (effect size=0.26; beta=−0.12, 95% CI −7.96 to 0.03, P=.05). Intention-to-treat analyses also indicated no statistically significant effect. Separate analyses of the 2 experimental subgroups showed no differences in intervention effects. The dropout rate during the first visit to the intervention website was significantly lower in the alternating condition than in the summative condition (OR 0.23, 95% CI 0.08-0.60, P=.003). Program appreciation was comparable for the 2 experimental groups.
Complete case analyses revealed that Web-based tailored feedback can be an effective way to reduce alcohol intake among adults. However, this effect was not confirmed when applying multiple imputations. There was no indication that one of the tailoring strategies was more effective in lowering alcohol intake. Nevertheless, the lower attrition rates we found during the first visit suggest that the version of the intervention with alternating questions and advice may be preferred.
Trial Registration
International Standard Randomized Controlled Trial Number (ISRCTN): 91623132; (Archived by WebCite at
PMCID: PMC3785997  PMID: 24045005
alcohol intake; adults; eHealth; computer tailoring; Web-based intervention; tailoring methods; effectiveness

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