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1.  Establishing a Common Metric for Physical Function: Linking the HAQ-DI and SF-36 PF Subscale to PROMIS® Physical Function 
Journal of General Internal Medicine  2015;30(10):1517-1523.
Physical function (PF) is a common health concept measured in clinical trials and clinical care. It is measured with different instruments that are not directly comparable, making comparative effectiveness research (CER) challenging when PF is the outcome of interest.
Our goal was to establish a common reporting metric, so that scores on commonly used physical function measures can be converted into PROMIS scores.
Following a single-sample linking design, all participants completed items from the NIH Patient Reported Outcomes Measurement Information System (PROMIS®) Physical Function (PROMIS PF) item bank and at least one other commonly used “legacy” measure: the Health Assessment Questionnaire (HAQ) or the Short Form–36 physical function ten-item PF scale (SF-36 PF). A common metric was created using analyses based on item response theory (IRT), producing score cross-walk tables.
Participants (N = 733) were part of an internet panel, many of whom reported one or more chronic health conditions.
PROMIS PF, SF-36 PF, and the HAQ–Disability Index (HAQ-DI).
Our results supported the hypothesis that all three scales measure essentially the same concept. Cross-walk tables for use in CER are therefore justified.
HAQ-DI and SF-36 PF results can be expressed on the PROMIS PF metric for the purposes of CER and other efforts to compare PF results across studies that utilize any one of these three measures. Clinicians seeking to incorporate PROs into their clinics can collect patient data on any one of these three instruments and estimate the equivalent on the other two.
Electronic supplementary material
The online version of this article (doi:10.1007/s11606-015-3360-0) contains supplementary material, which is available to authorized users.
PMCID: PMC4579209  PMID: 25990189
patient-reported outcome; PRO; score linking; SF-36; HAQ-DI; PROMIS; physical function
2.  US Valuation of Health Outcomes Measured Using the PROMIS-29 
Health valuation studies enhance economic evaluations of treatments by estimating the value of health-related quality of life (HRQoL). The Patient-Reported Outcomes Measurement Information System® (PROMIS) includes a 29-item short-form HRQOL measure, the PROMIS-29.
To value PROMIS-29 responses on a quality-adjusted life year (QALY) scale, we conducted a national survey (N=7557) using quota sampling based on the US 2010 Census. Based on 541 paired comparisons with over 350 responses each, pair-specific probabilities were incorporated into a weighted least-squared estimator.
All losses in HRQoL influenced choice; however, respondents valued losses in physical function, anxiety, depression, sleep, and pain more than those in fatigue and social functioning.
This paper introduces a novel approach to valuing HRQoL for economic evaluations using paired comparisons and provides a tool to translate PROMIS-29 responses into QALYs.
PMCID: PMC4471856  PMID: 25498780
Quality-adjusted life years; discrete choice experiments; patient-reported outcomes
3.  Adolescent body weight and health-related quality of life rated by adolescents and parents: the issue of measurement bias 
BMC Public Health  2015;15:1192.
Evidence is sparse about whether body weight categories in adolescents are associated with differences in pediatric HRQoL rated by adolescents and parents. Additionally, it is unknown whether HRQoL rated by individuals with different body mass index (BMI) weight categories is psychometrically comparable. This study aimed to assess whether difference in pediatric HRQoL rated by adolescents and their parents was explained by BMI weight status, and to test measurement properties of HRQoL items related to weight categories using differential item functioning (DIF) methodology. DIF refers to the situation when the individuals across subgroups rate an item differently (e.g., item score three by one subgroup and four by another) given the same underlying construct.
A cross-sectional study utilizing a sample of parents (n = 323) and their adolescents aged 15–18 years old (n = 323) who enrolled in Florida’s Medicaid. Adolescent self-reports and parent proxy-reports of the Pediatric Quality of Life Inventory was adopted to measure pediatric HRQoL. We classified body weight categories as normal weight, overweight, and obesity. A Multiple Indicator Multiple Cause (MIMIC) method was used to assess DIF associated with BMI weight status, especially testing the disparity in the parameters of different weight categories (reference: lower weight category) associated with a response to a HRQoL item conditioning on the same underlying HRQoL. DIF analyses were conducted by adolescent self-reports and parent proxy-reports.
Parents reported lower pediatric HRQoL across all domains than adolescents did. Excess body weight (combined overweight and obese) was significantly associated with a greater discrepancy in the rating of emotional and total functioning between adolescents and parents (p < 0.05). DIF associated with BMI weight categories was identified by two items in adolescent self-reports and five items in parent proxy-reports.
Adolescents’ BMI weight categories significantly contribute to a difference in the rating of pediatric HRQoL by adolescents and parents.
PMCID: PMC4663736  PMID: 26619909
Adolescents; Differential item functioning; Health-related quality of life; Obesity; Measurement bias
4.  Comparison of four pediatric health-related quality of life Instruments: a study on a Medicaid population 
Few studies have compared multiple health-related quality of life (HRQOL) instruments simultaneously for pediatric populations. This study aimed to test psychometric properties of four legacy pediatric HRQOL instruments: the Child Health and Illness Profile (CHIP), the KIDSCREEN-52, the KINDL, and the Pediatric Quality of Life Inventory (PedsQL).
This study used data of 908 parents whose children (ages 2–19) were enrolled in Florida Medicaid. Parents were asked via telephone interview to complete each instrument appropriate to the age of their children. Structural, convergent/discriminant, and known-group validities were investigated. We examined structural validity using confirmatory factor analyses. We examined convergent/discriminant validity by comparing Spearman rank correlation coefficients of homogeneous (physical functioning and physical well-being) vs. heterogeneous (physical and psychological functioning) domains of the instruments. We assessed known-groups validity by examining the extent to which HRQOL differed by the status of children with special health needs (CSHCN).
Domain scores of the four instruments were not normally distributed and ceiling effects were significant in most domains. The KIDSCREEN-52 demonstrates the best structural validity, followed by the CHIP and the KINDL, and the PedsQL. The PedsQL and the KIDSCREEN-52 show better convergent/discriminant validity than the other instruments. Known-groups validity in discriminating CSHCN versus no needs was the best for the PedsQL, followed by the KIDSCREEN-52, the CHIP, and the KINDL.
No one instrument was fully satisfactory in all psychometric properties. Strategies are recommended for future comparison of item content and measurement properties across different HRQOL instruments for research and clinical use.
PMCID: PMC4199940  PMID: 24739533
5.  The PROMIS of QALYs 
Measuring health and health-related quality of life (HRQoL) is important for tracking the health of individuals and populations over time. Generic HRQoL measures allow for comparison across health conditions. One form of generic HRQoL measures are profile measures, which provide a description of health across several different domains (such as physical functioning, depression, and pain). Recent advances in health profile measurement include the development of measures based on item response theory. The Patient-Reported Outcomes Measurement Information System (PROMIS®) has been constructed using this theory. Another form of generic HRQoL measures are utility measures, which assess the value of health states. Multi-attribute utility theory provides a framework for valuing disparate domains of health and aggregating them into a single preference-based score. Such a score provides an overall measure of health outcomes as well as a quality of life weight for use in decision analyses and cost-effectiveness analyses. Developing a utility score for PROMIS® would allow simultaneous estimation of both health profile and utility scores using a single measure. The purpose of this paper is to provide a roadmap of the methodological steps necessary to create such a scoring system.
PMCID: PMC4530486  PMID: 26260491
6.  Calibration and Validation of the Dutch-Flemish PROMIS Pain Interference Item Bank in Patients with Chronic Pain 
PLoS ONE  2015;10(7):e0134094.
The Dutch-Flemish PROMIS Group translated the adult PROMIS Pain Interference item bank into Dutch-Flemish. The aims of the current study were to calibrate the parameters of these items using an item response theory (IRT) model, to evaluate the cross-cultural validity of the Dutch-Flemish translations compared to the original English items, and to evaluate their reliability and construct validity. The 40 items in the bank were completed by 1085 Dutch chronic pain patients. Before calibrating the items, IRT model assumptions were evaluated using confirmatory factor analysis (CFA). Items were calibrated using the graded response model (GRM), an IRT model appropriate for items with more than two response options. To evaluate cross-cultural validity, differential item functioning (DIF) for language (Dutch vs. English) was examined. Reliability was evaluated based on standard errors and Cronbach’s alpha. To evaluate construct validity correlations with scores on legacy instruments (e.g., the Disabilities of the Arm, Shoulder and Hand Questionnaire) were calculated. Unidimensionality of the Dutch-Flemish PROMIS Pain Interference item bank was supported by CFA tests of model fit (CFI = 0.986, TLI = 0.986). Furthermore, the data fit the GRM and showed good coverage across the pain interference continuum (threshold-parameters range: -3.04 to 3.44). The Dutch-Flemish PROMIS Pain Interference item bank has good cross-cultural validity (only two out of 40 items showing DIF), good reliability (Cronbach’s alpha = 0.98), and good construct validity (Pearson correlations between 0.62 and 0.75). A computer adaptive test (CAT) and Dutch-Flemish PROMIS short forms of the Dutch-Flemish PROMIS Pain Interference item bank can now be developed.
PMCID: PMC4516300  PMID: 26214178
7.  A Checklist for Reporting Valuation Studies of Multi-Attribute Utility-Based Instruments (CREATE) 
Pharmacoeconomics  2015;33(8):867-877.
Multi-attribute utility-based instruments (MAUIs) assess health status and provide an index score on the full health-dead scale, and are widely used to support reimbursement decisions for new healthcare interventions worldwide. A valuation study is a key part of the development of MAUIs, with the primary goal of developing a scoring algorithm through eliciting societal preferences. We developed the 21-item Checklist for REporting VAluaTion StudiEs (CREATE) by following a modified two-round Delphi panel approach plus an email survey. CREATE is intended to promote good reporting practice as well as guiding developers to thoroughly and carefully think through key methodological elements in designing valuation studies.
Electronic supplementary material
The online version of this article (doi:10.1007/s40273-015-0292-9) contains supplementary material, which is available to authorized users.
PMCID: PMC4519579  PMID: 26026667
8.  Demographic Differences in Health Preferences in the United States 
Medical care  2014;52(4):307-313.
The United States has a culturally and demographically diverse populace, and the aim of this study was to examine differences in health preferences by gender, age, ethnicity, and race.
We assessed preferences for health outcomes defined by the PROMIS-29 survey in a sample of the U.S. population. Based on the survey’s 540 paired comparisons trading off lifespan and 7 domains of health-related quality of life (HRQoL), we compared the choices between men and women, adults age 18 to 54 years and 55 years and older, Hispanics and non-Hispanics and non-Hispanic Blacks and Whites. For each subgroup, we estimated the value of 122 HRQoL outcomes on a quality-adjusted life year (QALY) scale and tested for subgroup differences.
Compared to men, women preferred reduced lifespan over losses in HRQoL, particularly for depression. Compared to the younger adults, older adults preferred reduced lifespan over the symptoms of depression, anxiety, and fatigue. Compared to non-Hispanic Whites, Hispanics preferred reduced lifespan over depression and sleep disturbance, but held similar values on losses in physical functioning. Among non-Hispanics, Blacks preferred reduced lifespan over losses in ability to climb stairs and to fall asleep compared to Whites, but held similar values on mental health outcomes.
With the growing emphasis on patient-centeredness and culturally sensitive treatment, it is important to recognize the diversity in values placed on potential losses in HRQoL, particularly mental health outcomes. Demographic differences in preferences may influence comparative or cost effectiveness of treatments as perceived by one or another subgroup.
PMCID: PMC4031273  PMID: 24374420
Quality-adjusted life years; discrete choice experiments; patient-reported outcomes; preferences; Health-related Quality of Life (HRQoL)
10.  Development of a Preference-Based Index from the National Eye Institute Visual Function Questionnaire-25 
JAMA ophthalmology  2014;132(3):310-318.
Understanding how individuals value health states is central to patient-centered care and to health policy decision making. Generic preference-based measures of health may not effectively capture the impact of ocular diseases. Recently, 6 items from the National Eye Institute Visual Function Questionnaire-25 were used to develop the Visual Function Questionnaire-Utility Index health state classification, which defines visual function health states.
To describe elicitation of preferences for health states generated from the Visual Function Questionnaire-Utility Index health state classification and development of an algorithm to estimate health preference scores for any health state.
Non-intervention, cross-sectional study.
General community in four countries (Australia, Canada, United Kingdom, and United States)
607 adult participants recruited from local newspaper advertisements. In the United Kingdom, an existing database of participants from previous studies was used for recruitment.
Eight out of 15,625 possible health states from the Visual Function Questionnaire-Utility Index were valued using time trade-off technique.
Main Outcome Measures
A theta severity score was calculated for Visual Function Questionnaire-Utility Index–defined health states using item response theory analysis. Regression models were then used to develop an algorithm to assign health state preference values for all potential health states defined by the Visual Function Questionnaire-Utility Index.
Health state preference values for the 8 states ranged from 0.343 (standard deviation, 0.395) to 0.956 (0.124). As expected, preference values declined with worsening visual function. Results indicate that the Visual Function Questionnaire-Utility Index describes states that participants view as spanning most of continuum from full health to dead.
Conclusions and Relevance
Visual Function Questionnaire-Utility Index health state classification produces health preference scores that can be estimated in vision-related studies that include National Eye Institute Visual Function Questionnaire-25. These preference scores may be of value for estimating utilities in economic and health policy analyses.
PMCID: PMC4357476  PMID: 24435696
11.  Qualitative Research on Fatigue Associated with Depression: Content Validity of the Fatigue Associated with Depression Questionnaire (FAsD-V2) 
The Patient  2015;8(5):433-443.
Fatigue is one of the most common symptoms of major depressive disorder (MDD). The Fatigue Associated with Depression Questionnaire (FAsD) was developed to assess fatigue and its impact in patients with MDD. The current article presents the qualitative research conducted to develop and examine the content validity of the FAsD and FASD–Version 2 (FAsD–V2).
Three phases of qualitative research were conducted with patients recruited from a geographically diverse range of clinics in the US. Phase I included concept elicitation focus groups, followed by cognitive interviews. Phase II employed similar techniques in a more targeted sample. Phase III included cognitive interviews to examine whether minor edits made after Phase II altered comprehensibility of the instrument. Concept elicitation focused on patients’ perceptions of fatigue and its impact. Cognitive interviews focused on comprehension, clarity, relevance, and comprehensiveness of the instrument. Data were collected using semi-structured discussion guides. Thematic analyses were conducted and saturation was examined.
A total of 98 patients with MDD were included. Patients’ statements during concept elicitation in phases I and II supported item development and content. Cognitive interviews supported the relevance of the instrument in the target population, and patients consistently demonstrated a good understanding of the instructions, items, response options, and recall period. Minor changes to instructions for the FAsD–V2 did not affect interpretation of the instrument.
This qualitative research supports the content validity of the FAsD and FAsD–V2. These results add to previous quantitative psychometric analysis suggesting the FAsD–V2 is a useful tool for assessing fatigue and its impact in patients with MDD.
PMCID: PMC4575372  PMID: 25613915
12.  The linkage between pediatric quality of life and health conditions: establishing clinically meaningful cutoff scores for the PedsQL 
To link pediatric health-related quality of life (HRQOL) and health conditions by establishing clinically meaningful cutoff scores for a HRQOL instrument, the PedsQL.
We conducted telephone interviews with 1745 parents whose children were between 2–18 years old and enrolled in the Florida KidCare program and Children’s Medical Services Network in 2006. Two anchors, the Children with Special Health Care Needs (CSHCN) Screener and the Clinical Risk Groups (CRGs), were used to identify children with special health care needs or chronic conditions. We established cutoff scores for the PedsQL’s physical, emotional, social, school, and total functioning using the areas under the curves (AUCs) to determine the discriminative property of the PedsQL referring to the anchors.
The discriminative property of the PedsQL was superior, especially in total functioning (AUC > 0.7), between children with special health care needs (based on the CSHCN Screener) and with moderate and major chronic conditions (based on the CRGs) as compared to healthy children. For children < 8 years, the recommended cutoff scores for using total functioning to identify CSHCN were 83, 79 for moderate and 77 for major chronic conditions. For children ≥ 8 years, the cutoff scores were 78, 76 and 70, respectively.
Pediatric HRQOL varied with health conditions. Establishing cutoff scores for the PedsQL’s total functioning is a valid and convenient means to potentially identify children with special health care needs or chronic conditions. The cutoff sores can help clinicians to conduct further in-depth clinical assessments.
PMCID: PMC4299816  PMID: 19508660
Children; clinically meaningful difference; cutoff; health-related quality of life; PedsQL
Pain  2013;154(12):10.1016/j.pain.2013.08.024.
Pain behaviors that are maintained beyond the acute stage post-injury can contribute to subsequent psychosocial and physical disability. Critical to the study of pain behaviors is the availability of psychometrically sound pain behavior measures. In this study we developed a self-report measure of pain behaviors, the Pain Behaviors Self Report (PaB-SR). PaB-SR scores were developed using item response theory and evaluated using a rigorous, multiple-witness approach to validity testing. Participants included: a) 661 survey participants with chronic pain and with multiple sclerosis (MS), back pain, or arthritis; b) 618 survey participants who were significant others of a chronic pain participant; and c) 86 participants in a videotaped pain behavior observation protocol. Scores on the PaB-SR were found to be measurement invariant with respect to clinical condition. PaB-SR scores, observer-reports, and the video-taped protocol yielded distinct, but convergent views of pain behavior, supporting the validity of the new measure. The PaB-SR is expected to be of substantial utility to researchers wishing to explore the relationship between pain behaviors and constructs such as pain intensity, pain interference, and disability.
PMCID: PMC3875313  PMID: 23994451
Chronic pain; assessment; psychometrics
14.  Developing Item Banks for Measuring Pediatric Generic Health-Related Quality of Life: An Application of the International Classification of Functioning, Disability and Health for Children and Youth and Item Response Theory 
PLoS ONE  2014;9(9):e107771.
The purpose of this study was to develop item banks by linking items from three pediatric health-related quality of life (HRQoL) instruments using a mixed methodology. Secondary data were collected from 469 parents of children aged 8-16 years. The International Classification of Functioning, Disability and Health-Children and Youth (ICF-CY) served as a framework to compare the concepts of items from three HRQoL instruments. The structural validity of the individual domains was examined using confirmatory factor analyses. Samejima's Graded Response Model was used to calibrate items from different instruments. The known-groups validity of each domain was examined using the status of children with special health care needs (CSHCN). Concepts represented by the items in the three instruments were linked to 24 different second-level categories of the ICF-CY. Eight item banks representing eight unidimensional domains were created based on the linkage of the concepts measured by the items of the three instruments to the ICF-CY. The HRQoL results of CSHCN in seven out of eight domains (except personality) were significantly lower compared with children without special health care needs (p<0.05). This study demonstrates a useful approach to compare the item concepts from the three instruments and to generate item banks for a pediatric population.
PMCID: PMC4182329  PMID: 25268926
15.  The relationships between asthma control, daytime sleepiness, and quality of life among children with asthma: a path analysis 
Sleep medicine  2013;14(7):641-647.
We aimed to examine the relationships between asthma control, daytime sleepiness, and asthma-specific health-related quality of life (HRQOL) among children with asthma. Path analyses were conducted to test if daytime sleepiness can mediate the effect of asthma control status on asthma-specific HRQOL.
160 dyads of asthmatic children and their parents were collected for analyses. The Asthma Control and Communication Instrument (ACCI) was used to categorize adequate and poor asthma control status. The Cleveland Adolescent Sleepiness Questionnaire (CASQ) was used to measure children’s daytime sleepiness, including sleep in school, awake in school, sleep in evening, and sleep during transport. The Patient-Reported Outcomes Measurement Information System (PROMIS) Asthma Impact Scale was used to measure asthma-specific HRQOL.
Poorly controlled asthma was associated with daytime sleepiness and impaired asthma-specific HRQOL. Asthma control status was directly associated with asthma-specific HRQOL (P<.05), whereas sleep in school and sleep in evening domains of daytime sleepiness significantly mediated the relationship between poor asthma control and impaired HRQOL (P<.01).
Asthma control status was associated with pediatric asthma-specific HRQOL, and the association was significantly mediated by daytime sleepiness. Healthcare providers need to address pediatric sleep needs related to poor asthma control to reduce the impact on HRQOL.
PMCID: PMC3715592  PMID: 23684939
Asthma control; children; health-related quality of life; patient-reported outcomes; sleepiness; structural equation modeling
16.  A history of health-related quality of life outcomes in psychiatry 
Health-related quality of life (HRQoL) is a multidimensional concept that includes subjective reports of symptoms, side effects, functioning in multiple life domains, and general perceptions of life satisfaction and quality. Rather than estimating it from external observations, interview, or clinical assessment, it is best measured by direct query. Due to a perception that respondents may not be reliable or credible, there has been some reluctance to use self-report outcomes in psychiatry. More recently, and increasingly, HRQoL assessment through direct patient query has become common when evaluating a range of psychiatric, psychological, and social therapies. With few exceptions, psychiatric patients are credible and reliable reporters of this information. This article summarizes studies that highlight the development, validation, and application of HRQoL measures in psychiatry. Thoughtful application of these tools in psychiatric research can provide a much-needed patient perspective in the future of comparative effectiveness research, patient-centered outcomes research, and clinical care.
PMCID: PMC4140507  PMID: 25152652
health-related quality of life; quality of life; psychiatric outcome; psychiatric symptom; patient-reported outcome
17.  Measurement invariance of the PROMIS pain interference item bank across community and clinical samples 
This study examined the measurement invariance of responses to the patient-reported outcomes measurement information system (PROMIS) pain interference (PI) item bank. The original PROMIS calibration sample (Wave I) was augmented with a sample of persons recruited from the American Chronic Pain Association (ACPA) to increase the number of participants reporting higher levels of pain. Establishing measurement invariance of an item bank is essential for the valid interpretation of group differences in the latent concept being measured.
Multi-group confirmatory factor analysis (MG-CFA) was used to evaluate successive levels of measurement invariance: configural, metric, and scalar invariance.
Support was found for configural and metric invariance of the PROMIS-PI, but not for scalar invariance.
Conclusions and recommendations
Based on our results of MG-CFA, we recommend retaining the original parameter estimates obtained by combining the community sample of Wave I and ACPA participants. Future studies should extend this study by examining measurement equivalence in an item response theory framework such as differential item functioning analysis.
PMCID: PMC3873645  PMID: 22552604
Factor analysis; Pain interference; Pain measurement; Patient outcome measures; Psychometrics
18.  The case for an international patient-reported outcomes measurement information system (PROMIS®) initiative 
Patient-reported outcomes (PROs) play an increasingly important role in clinical practice and research. Modern psychometric methods such as item response theory (IRT) enable the creation of item banks that support fixed-length forms as well as computerized adaptive testing (CAT), often resulting in improved measurement precision and responsiveness. Here we describe and discuss the case for developing an international core set of PROs building from the US PROMIS® network.
PROMIS is a U.S.-based cooperative group of research sites and centers of excellence convened to develop and standardize PRO measures across studies and settings. If extended to a global collaboration, PROMIS has the potential to transform PRO measurement by creating a shared, unifying terminology and metric for reporting of common symptoms and functional life domains. Extending a common set of standardized PRO measures to the international community offers great potential for improving patient-centered research, clinical trials reporting, population monitoring, and health care worldwide. Benefits of such standardization include the possibility of: international syntheses (such as meta-analyses) of research findings; international population monitoring and policy development; health services administrators and planners access to relevant information on the populations they serve; better assessment and monitoring of patients by providers; and improved shared decision making.
The goal of the current PROMIS International initiative is to ensure that item banks are translated and culturally adapted for use in adults and children in as many countries as possible. The process includes 3 key steps: translation/cultural adaptation, calibration, and validation. A universal translation, an approach focusing on commonalities, rather than differences across versions developed in regions or countries speaking the same language, is proposed to ensure conceptual equivalence for all items. International item calibration using nationally representative samples of adults and children within countries is essential to demonstrate that all items possess expected strong measurement properties. Finally, it is important to demonstrate that the PROMIS measures are valid, reliable and responsive to change when used in an international context.
IRT item banking will allow for tailoring within countries and facilitate growth and evolution of PROs through contributions from the international measurement community. A number of opportunities and challenges of international development of PROs item banks are discussed.
PMCID: PMC3879205  PMID: 24359143
Patient-reported outcomes; Health-related quality of life research; Patients’ experiences; Questionnaires; Cross-cultural equivalence; Health information systems; Clinical decision making; Comparative effectiveness research; Patient empowerment; Cross-national comparisons
19.  Comparison of US Panel Vendors for Online Surveys 
Despite the increasing use of panel surveys, little is known about the differences in data quality across panels.
The aim of this study was to characterize panel survey companies and their respondents based on (1) the timeliness of response by panelists, (2) the reliability of the demographic information they self-report, and (3) the generalizability of the characteristics of panelists to the US general population. A secondary objective was to highlight several issues to consider when selecting a panel vendor.
We recruited a sample of US adults from 7 panel vendors using identical quotas and online surveys. All vendors met prespecified inclusion criteria. Panels were compared on the basis of how long the respondents took to complete the survey from time of initial invitation. To validate respondent identity, this study examined the proportion of consented respondents who failed to meet the technical criteria, failed to complete the screener questions, and provided discordant responses. Finally, characteristics of the respondents were compared to US census data and to the characteristics of other panels.
Across the 7 panel vendors, 2% to 9% of panelists responded within 2 days of invitation; however, approximately 20% of the respondents failed the screener, largely because of the discordance between self-reported birth date and the birth date in panel entry data. Although geographic characteristics largely agreed with US Census estimates, each sample underrepresented adults who did not graduate from high school and/or had annual incomes less than US $15,000. Except for 1 vendor, panel vendor samples overlapped one another by approximately 20% (ie, 1 in 5 respondents participated through 2 or more panel vendors).
The results of this head-to-head comparison provide potential benchmarks in panel quality. The issues to consider when selecting panel vendors include responsiveness, failure to maintain sociodemographic diversity and validated data, and potential overlap between panels.
PMCID: PMC3869084  PMID: 24292159
survey methods; community surveys; sampling bias; selection bias; Internet; data sources
20.  Asthma Symptom Utility Index: Reliability, validity, responsiveness and the minimal important difference in adult asthma patients 
The evaluation of asthma symptoms is a core outcome measure in asthma clinical research. The Asthma Symptom Utility Index (ASUI) was developed to assess frequency and severity of asthma symptoms. The psychometric properties of the ASUI are not well characterized and a minimal important difference (MID) is not established.
We assessed the reliability, validity, and responsiveness to change of the ASUI in a population of adult asthma patients. We also sought to determine the MID for the ASUI.
Adult asthma patients (n = 1648) from two previously completed multicenter randomized trials were included. Demographic information, spirometry, ASUI scores, and other asthma questionnaire scores were obtained at baseline and during follow-up visits. Participants also kept a daily asthma diary.
Internal consistency reliability of the ASUI was 0.74 (Cronbach’s alpha). Test-retest reliability was 0.76 (intra-class correlation). Construct validity was demonstrated by significant correlations between ASUI scores and Asthma Control Questionnaire (ACQ) scores (Spearman correlation r = −0.79, 95% CI [−0.85, −0.75], P<0.001) and Mini Asthma Quality of Life Questionnaire (Mini AQLQ) scores (r = 0.59, 95% CI [0.51, 0.61], P<0.001). Responsiveness to change was demonstrated, with significant differences between mean changes in ASUI score across groups of participants differing by 10% in the percent predicted FEV1 (P<0.001), and by 0.5 points in ACQ score (P < 0.001). Anchor-based methods and statistical methods support an MID for the ASUI of 0.09 points.
The ASUI is reliable, valid, and responsive to changes in asthma control over time. The MID of the ASUI (range of scores 0–1) is 0.09.
PMCID: PMC3501248  PMID: 23026499
Asthma Symptom Utility Index; reliability; validity; responsiveness; minimal important difference
21.  Agreement was not found in adolescents’ quality of life rated by parents and adolescents 
Journal of clinical epidemiology  2008;62(3):10.1016/j.jclinepi.2008.06.012.
Limited evidence examines agreement between the ratings of adolescents’ health-related quality of life (HRQOL) by parents and adolescents especially accounting for measurement properties. This study aimed to test whether agreement exists between the dyads using a methodology of measurement invariance.
Study Design and Setting
We conducted a telephone survey to collect data from parents and their adolescents enrolled in Florida’s Children’s Medical Services (376 pairs) using the PedsQL 4.0. We used multi-group confirmatory factor analysis to test measurement invariance, including configural (equivalent HRQOL construct), metric (equivalent item–domain associations), scalar (equivalent starting value of ratings), and residual (equivalent nonsystematic measurement errors of ratings) invariance. We also investigated correlates of discrepancies in the dyadic ratings.
There were equivalent HRQOL constructs and item–domain associations between the dyads. However, some items show different starting values and nonsystematic errors in the dyadic ratings. After adjusting for noninvariant items, adolescents reported significant higher HRQOL scores than parents in all domains (P < 0.05). Parents’ rating of adolescents’ health significantly contributed to discrepancies in the dyadic ratings (P < 0.05).
Adolescents rated HRQOL higher than their parents. This discrepancy was associated with severe health conditions. Without assuring measurement invariance, comparisons of the dyadic HRQOL ratings can be misleading.
PMCID: PMC3812676  PMID: 18834712
Adolescent; Confirmatory factor analysis; Health-related quality of life; Health status; Proxy; Measurement invariance
22.  Using three legacy measures to develop a health-related quality of life tool for young adult survivors of childhood cancer 
Little attention has been paid to selecting and developing health-related quality of life (HRQOL) measurement tools for young adult survivors of childhood cancer (YASCC). The primary purpose of this study was to develop a HRQOL tool for YASCC based on three legacy instruments.
Data collected from 151 YASCC were analyzed. HRQOL was measured using the Medical Outcomes Study SF-36, Quality of Life in Adult Cancer Survivors, and Quality of Life-Cancer Survivor. We used the following stages to develop our HRQOL tool: mapping items from three instruments into a common HRQOL construct, checking dimensionality using confirmatory factor analyses (CFA), and equating items using Rasch modeling.
We assigned 123 items to a HRQOL construct comprised of six generic and eight survivor-specific domains. CFA retained 107 items that meet the assumptions of unidimensionality and local independence. Rasch analysis retained 68 items that satisfied the indices of information-weighted/outlier-sensitive fit statistic mean square. However, items in most domains possess relatively easy measurement properties, whereas YASCC’s underlying HRQOL was on the middle to higher levels.
Psychometric properties of the established tool for measuring HRQOL of YASCC were not satisfied. Future studies need to refine this tool, especially adding more challenging items.
PMCID: PMC3328688  PMID: 22101901
Childhood cancer; measurement; quality of life; Rasch analysis; young adult survivor
23.  Determining the clinically important difference in visual analog scale scores in abuse liability studies evaluating novel opioid formulations 
This study determined how the magnitude of change in positive subjective responses predicts clinical outcome in a treatment setting. Specifically, we attempted to define what constitutes a clinically important difference (CID) in subjective responses.
A 100-mm visual analog scale (VAS) measured subjective ratings of drug “high,” calculated via an anchor-based method with published data from participants receiving sustained-release naltrexone (NTX) and heroin in a laboratory setting. The data were then compared to clinical outcomes in a treatment trial with sustained-release naltrexone. A distribution-based method subsequently analyzed data from participants who received ALO-01 (extended-release morphine with sequestered NTX) to predict its abuse liability.
Differences in ratings of drug high of approximately 10 mm on a 100-mm line were clinically significant. By extrapolation, CIDs were also found between crushed or intact ALO-01 and immediate-release morphine sulfate (IRMS). No CIDs were found between intact and crushed ALO-01.
From laboratory and treatment trial data involving naltrexone, calculation of CIDs in subjective ratings of high is possible. Consequently, crushing/swallowing or injecting ALO-01 produces clinically significantly less drug high than oral or intravenous morphine alone, suggesting that ALO-01 has lower abuse liability by those routes than morphine formulations.
PMCID: PMC3628592  PMID: 21964915
Analgesics; Opioid; Drug formulations; Morphine; Drug high; Abuse liability
24.  Exploring factors influencing asthma control and asthma-specific health-related quality of life among children 
Respiratory Research  2013;14(1):26.
Little is known about factors contributing to children’s asthma control status and health-related quality of life (HRQoL). The study objectives were to assess the relationship between asthma control and asthma-specific HRQoL in asthmatic children, and to examine the extent to which parental health literacy, perceived self-efficacy with patient-physician interaction, and satisfaction with shared decision-making (SDM) contribute to children’s asthma control and asthma-specific HRQoL.
This cross-sectional study utilized data collected from a sample of asthmatic children (n = 160) aged 8–17 years and their parents (n = 160) who visited a university medical center. Asthma-specific HRQoL was self-reported by children using the National Institutes of Health’s Patient-Reported Outcomes Measurement Information System (PROMIS) Pediatric Asthma Impact Scale. Satisfaction with SDM, perceived self-efficacy with patient-physician interaction, parental health literacy, and asthma control were reported by parents using standardized measures. Structural equation modeling (SEM) was performed to test the hypothesized pathways.
Path analysis revealed that children with better asthma control reported higher asthma-specific HRQoL (β = 0.4, P < 0.001). Parents with higher health literacy and greater perceived self-efficacy with patient-physician interactions were associated with higher satisfaction with SDM (β = 0.38, P < 0.05; β = 0.58, P < 0.001, respectively). Greater satisfaction with SDM was in turn associated with better asthma control (β = −0.26, P < 0.01).
Children’s asthma control status influenced their asthma-specific HRQoL. However, parental factors such as perceived self-efficacy with patient-physician interaction and satisfaction with shared decision-making indirectly influenced children’s asthma control status and asthma-specific HRQoL.
PMCID: PMC3599064  PMID: 23432913
Asthma control; Health-related quality of life; PROMIS; Satisfaction with shared decision-making; Perceived self-efficacy with patient-physician interaction; Structural equation modeling
25.  Patient-reported outcomes in randomized clinical trials: development of ISOQOL reporting standards 
Quality of Life Research  2012;22(6):1161-1175.
To develop expert consensus on a suite of reporting standards for HRQL outcomes of RCTs.
A Task Force of The International Society of Quality of Life Research (ISOQOL) undertook a systematic review of the literature to identify candidate reporting standards for HRQL in RCTs. Subsequently, a web-based survey was circulated to the ISOQOL membership. Respondents were asked to rate candidate standards on a 4-point Likert scale based on their perceived value in reporting studies in which HRQL was a study outcome (primary or secondary). Results were synthesized into draft reporting guidelines, which were further reviewed by the membership to inform the final guidance.
Forty-six existing candidate standards for reporting HRQL results in RCTs were synthesized to produce a 40 item survey that was completed electronically by 161 respondents. The majority of respondents rated all 40 items to be either ‘essential’ or ‘desirable’ when HRQL was a primary RCT outcome. Ratings changed when HRQL was a secondary study outcome. Feedback on the survey findings resulted in the Task Force generalizing the guidance to include patient-reported outcomes (PROs). The final guidance, which recommends standards for use in reporting PROs generally, and more specifically, for PROs identified as primary study outcomes, was approved by the ISOQOL Board of Directors.
ISOQOL has developed a suite of recommended standards for reporting PRO results of RCTs. Improved reporting of PROs will enable accurate interpretation of evidence to inform patient choice, aid clinical decision making, and inform health policy.
PMCID: PMC3731511  PMID: 22987144
Reporting; Randomized clinical trials; Quality of life; Patient-reported outcomes; Guidelines

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