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1.  Cost-effectiveness of diacetylmorphine versus methadone for chronic opioid dependence refractory to treatment 
Background:
Although diacetylmorphine has been proven to be more effective than methadone maintenance treatment for opioid dependence, its direct costs are higher. We compared the cost-effectiveness of diacetylmorphine and methadone maintenance treatment for chronic opioid dependence refractory to treatment.
Methods:
We constructed a semi-Markov cohort model using data from the North American Opiate Medication Initiative trial, supplemented with administrative data for the province of British Columbia and other published data, to capture the chronic, recurrent nature of opioid dependence. We calculated incremental cost-effectiveness ratios to compare diacetylmorphine and methadone over 1-, 5-, 10-year and lifetime horizons.
Results:
Diacetylmorphine was found to be a dominant strategy over methadone maintenance treatment in each of the time horizons. Over a lifetime horizon, our model showed that people receiving methadone gained 7.46 discounted quality-adjusted life-years (QALYs) on average (95% credibility interval [CI] 6.91–8.01) and generated a societal cost of $1.14 million (95% CI $736 800–$1.78 million). Those who received diacetylmorphine gained 7.92 discounted QALYs on average (95% CI 7.32–8.53) and generated a societal cost of $1.10 million (95% CI $724 100–$1.71 million). Cost savings in the diacetylmorphine cohort were realized primarily because of reductions in the costs related to criminal activity. Probabilistic sensitivity analysis showed that the probability of diacetylmorphine being cost-effective at a willingness-to-pay threshold of $0 per QALY gained was 76%; the probability was 95% at a threshold of $100 000 per QALY gained. Results were confirmed over a range of sensitivity analyses.
Interpretation:
Using mathematical modelling to extrapolate results from the North American Opiate Medication Initiative, we found that diacetylmorphine may be more effective and less costly than methadone among people with chronic opioid dependence refractory to treatment.
doi:10.1503/cmaj.110669
PMCID: PMC3314060  PMID: 22410375
2.  Medical profiteering: the economics of methadone dispensation 
doi:10.1503/cmaj.081513
PMCID: PMC2683216  PMID: 19468111
3.  Cost-effectiveness of Newer Antiretroviral Drugs in Treatment-Experienced Patients with Multi-drug Resistant HIV Disease 
Objective
Newer antiretroviral drugs provide substantial benefits but are expensive. We determined the cost-effectiveness of using antiretroviral drugs in combination for patients with multi-drug resistant HIV disease.
Design
We built a cohort state-transition model representing treatment-experienced patients with low CD4 counts, high viral load levels, and multi-drug resistant virus. We estimated the effectiveness of newer drugs (those approved in 2005 or later) from published randomized trials. We estimated other parameters from a randomized trial and from the literature. The model had a lifetime time horizon and used the perspective of an ideal insurer in the United States. The interventions were combination antiretroviral therapy, consisting of two newer drugs and one conventional drug, compared to three conventional drugs. Outcome measures were life-years, quality-adjusted life-years (QALYs), costs, and incremental cost-effectiveness.
Results
Substituting newer antiretroviral drugs increased expected survival by 3.9 years in advanced HIV disease. The incremental cost-effectiveness ratio of newer, compared to conventional, antiretroviral drugs was $75,556/QALY gained. Sensitivity analyses showed that substituting only one newer antiretroviral drug cost $54,559 to $68,732/QALY, depending on assumptions about efficacy. Substituting three newer drugs cost $105,956 to $117,477/QALY. Cost-effectiveness ratios were higher if conventional drugs were not discontinued.
Conclusions
In treatment-experienced patients with advanced HIV disease, use of newer antiretroviral agents can be cost effective, given a cost-effectiveness threshold in the range of $50,000 to $75,000 per QALY gained. Newer antiretroviral agents should be used in carefully selected patients for whom less expensive options are clearly inferior.
doi:10.1097/QAI.0000000000000002
PMCID: PMC3932156  PMID: 24129369
Novel antiretroviral drugs; multi-drug resistant HIV infection; cost-effectiveness analysis; quality of life; health economics
5.  Risk of Type 2 Diabetes among Osteoarthritis Patients in a Prospective Longitudinal Study 
Objectives. Our aim was to determine the risk of diabetes among osteoarthritis (OA) cases in a prospective longitudinal study. Methods. Administrative health records of 577,601 randomly selected individuals from British Columbia, Canada, from 1991 to 2009, were analyzed. OA and diabetes cases were identified by checking physician's visits and hospital records. From 1991 to 1996 we documented 19,143 existing OA cases and selected one non-OA individual matched by age, sex, and year of administrative records. Poisson regression and Cox proportional hazards models were fitted to estimate the effects after adjusting for available sociodemographic and medical factors. Results. At baseline, the mean age of OA cases was 61 years and 60.5% were women. Over 12 years of mean follow-up, the incidence rate (95% CI) of diabetes was 11.2 (10.90–11.50) per 1000 person years. Adjusted RRs (95% CI) for diabetes were 1.27 (1.15–1.41), 1.21 (1.08–1.35), 1.16 (1.04–1.28), and 0.99 (0.86–1.14) for younger women (age 20–64 years), older women (age ≥ 65 years), younger men, and older men, respectively. Conclusion. Younger adults and older women with OA have increased risks of developing diabetes compared to their age-sex matched non-OA counterparts. Further studies are needed to confirm these results and to elucidate the potential mechanisms.
doi:10.1155/2014/620920
PMCID: PMC4236891  PMID: 25538769
6.  Differential long-term outcomes for voluntary and involuntary transition from injection to oral opioid maintenance treatment 
Background
The most widely used maintenance treatment for opioid dependency is substitution with long-acting oral opioids. Treatment with injectable diacetylmorphine provides an opportunity for patients to stabilize and possibly transition to oral treatment, if clinically indicated. The aim of this study was to explore outcomes of individuals that received injectable diacetylmorphine and voluntarily transitioned to oral methadone.
Design and methods
The North American Opiate Medication Initiative was a randomized controlled trial that compared the effectiveness of injectable diacetylmorphine (or hydromorphone) to oral methadone for long-term opioid-dependency. Treatment was provided for 12-months with an additional 3 months for transition and weaning. Participants were followed until 24-months from randomization. Among the participants randomized to injectable treatments, a sub-group voluntarily chose to transition to oral methadone (n = 16) during the treatment period. Illicit heroin use and treatment retention were assessed at 24-months for those voluntarily and involuntarily transitioning (n = 95) to oral methadone.
Results
At 24-months, the group that voluntarily transitioned to oral methadone had higher odds of treatment retention (adjusted odds ratio = 5.55; 95% confidence interval [CI] = 1.11, 27.81; Chi-square = 4.33, df = 1, p-value = 0.037) than the involuntary transition group. At 24-months, the adjusted mean difference in prior 30 days of illicit heroin use for the voluntary, compared to the involuntary group was -5.58 (95% CI = -11.62, 0.47; t-value = -1.83, df = 97.4, p-value = 0.070).
Conclusions
Although the results of this study were based on small groups of self-selected (i.e., non-randomized) participants, our data underlines the critical importance of voluntary and patient-centered decision making. If we had continued offering treatment with diacetylmorphine, those retained to injectable medication may have sustained the achieved improvements in the first 12 months. Diversified opioid treatment should be available so patients and physicians can flexibly choose the best treatment at the time.
Trial registration
Clinical Trial Registration: NCT00175357
doi:10.1186/1747-597X-9-23
PMCID: PMC4064505  PMID: 24908387
Opioid dependency; Diacetylmorphine, Injectable; Oral methadone; Opioid maintenance treatment
7.  A chance to stop and breathe: participants’ experiences in the North American Opiate Medication Initiative clinical trial 
Background
The North American Opiate Medication Initiative (NAOMI) clinical trial compared the effectiveness of injectable diacetylmorphine (DAM) or hydromorphone (HDM) to oral methadone maintenance treatment (MMT). This study aimed to determine participants’ perceptions of treatment delivered in NAOMI.
Methods
A qualitative sub-study was conducted with 29 participants (12 female): 18 (62.1%) received injectable DAM or HDM and 11 (37.9%) received MMT. A phenomenological theoretical framework was used. Semi-structured interviews were audio-recorded and transcribed verbatim. A thematic analysis was used over successive phases and was driven by the semantic meanings of the data.
Results
Participants receiving injectable medications suggested that the supervised delivery model was stringent but provided valuable stability to their lives. Females discussed the adjustment required for the clinical setting, while males focused on the challenging clinic schedule and its impact on employment abilities. Participants receiving MMT described disappointment with being randomized to this treatment; however, positive aspects, including the quick titration time and availability of auxiliary services, were also discussed.
Conclusion
Treatment with injectable DAM (or HDM) is preferred by participants and considered effective in reducing the burden of opioid dependency. Engaging patients in research regarding their perceptions of treatment provides a comprehensive assessment of treatment needs and barriers.
Clinical trial registration
NCT00175357
doi:10.1186/1940-0640-9-21
PMCID: PMC4181618  PMID: 25262567
Opioid dependency; Diacetylmorphine; Injectable; Oral methadone; Opioid maintenance treatment; Qualitative methods
8.  Factors associated with pretreatment and treatment dropouts: comparisons between Aboriginal and non-Aboriginal clients admitted to medical withdrawal management 
Background
Addiction treatment faces high pretreatment and treatment dropout rates, especially among Aboriginals. In this study we examined characteristic differences between Aboriginal and non-Aboriginal clients accessing an inpatient medical withdrawal management program, and identified risk factors associated with the probabilities of pretreatment and treatment dropouts, respectively.
Methods
2231 unique clients (Aboriginal = 451; 20%) referred to Vancouver Detox over a two-year period were assessed. For both Aboriginal and non-Aboriginal groups, multivariate logistic regression analyses were conducted with pretreatment dropout and treatment dropout as dependent variables, respectively.
Results
Aboriginal clients had higher pretreatment and treatment dropout rates compared to non-Aboriginal clients (41.0% vs. 32.7% and 25.9% vs. 20.0%, respectively). For Aboriginal people, no fixed address (NFA) was the only predictor of pretreatment dropout. For treatment dropout, significant predictors were: being female, having HCV infection, and being discharged on welfare check issue days or weekends. For non-Aboriginal clients, being male, NFA, alcohol as a preferred substance, and being on methadone maintenance treatment (MMT) at referral were associated with pretreatment dropout. Significant risk factors for treatment dropout were: being younger, having a preferred substance other than alcohol, having opiates as a preferred substance, and being discharged on weekends.
Conclusions
Our results highlight the importance of social factors for the Aboriginal population compared to substance-specific factors for the non-Aboriginal population. These findings should help clinicians and decision-makers to recognize the importance of social supports especially housing and initiate appropriate services to improve treatment intake and subsequent retention, physical and mental health outcomes and the cost-effectiveness of treatment.
doi:10.1186/1477-7517-10-38
PMCID: PMC3878858  PMID: 24325629
Aboriginal; Housing; Pretreatment dropout rate; Treatment dropout rate; Withdrawal management; Substance use disorders; Detoxification
9.  Defining dosing pattern characteristics of successful tapers following methadone maintenance treatment: Results from a population-based retrospective cohort study 
Addiction (Abingdon, England)  2012;107(9):1621-1629.
Aims
Identify dose tapering strategies associated with sustained success following methadone maintenance treatment (MMT).
Design
Population-based retrospective cohort study.
Setting
Linked administrative medication dispensation data from British Columbia, Canada.
Participants
From 25,545 completed MMT episodes, 14,602 of which initiated a taper, 4,183 individuals (accounting for 4,917 MMT episodes) from 1996–2006 met study inclusion criteria.
Measurements
The primary outcome was sustained successful taper, defined as a daily dose ≤5mg per day in the final week of the treatment episode and no treatment re-entry, opioid-related hospitalization, or mortality within 18 months following episode completion.
Findings
The overall rate of sustained success was 13% among episodes meeting inclusion criteria (646/4,917), 4.4% (646/14,602) among all episodes initiating a taper, and 2.5% (646/25,545) among all completed episodes in the dataset. The results of our multivariate logistic regression analyses suggested that longer tapers had substantially higher odds of success (12–52 weeks vs. <12 weeks: Odds ratio: 3.58; 95% confidence interval: 2.76 – 4.65); > 52 weeks vs. < 12 weeks: 6.68 (5.13 – 8.70)), regardless of how early in the treatment episode the taper was initiated, and a more gradual, stepped tapering schedule, with dose decreases scheduled in only 25–50% of the weeks of the taper, provided the highest odds of sustained success (vs. <25%: 1.61 (1.22–2.14)).
Conclusions
The majority of patients attempting to taper from methadone maintenance treatment will not succeed. Success is enhanced by gradual dose reductions interspersed with periods of stabilization. These results can inform the development of a more refined guideline for future clinical practice.
doi:10.1111/j.1360-0443.2012.03870.x
PMCID: PMC3376663  PMID: 22385013
10.  The relationship between osteoarthritis and cardiovascular disease in a population health survey: a cross-sectional study 
BMJ Open  2013;3(5):e002624.
Objectives
Our objective was to determine the relationship between osteoarthritis (OA) and heart diseases (myocardial infarction (MI), angina, congestive heart failure (CHF)) and stroke using population-based survey data.
Design
Cross-sectional study.
Setting
Canadian Community Health Survey (CCHS).
Participants
Adult participants in the CCHS cycles 1.1, 2.1 and 3.1 were included. CCHS provides nationally representative data on health determinants, health status and health system utilisation. We have identified 40 817 self-reported OA subjects and selected 1:1 matched non-OA respondents by age, sex and CCHS cycles.
Main outcome measures
Self-reported heart disease was the primary outcome and MI, angina, CHF and stroke were considered as secondary outcomes. Multivariable logistic regression models were used to estimate the ORs after adjusting for sociodemographic status, obesity, physical activity, smoking status, fruit and vegetable consumption, medication use, diabetes, hypertension and chronic obstructive pulmonary disease.
Results
The mean age of OA cases was 66 years and 71.6% were women. OA exhibited increased odds of prevalent heart disease, and adjusted overall OR (95% CI) was 1.45 (1.36 to 1.54), 1.35 (1.21 to 1.50) among men and 1.51 (1.39 to 1.64) among women with OA. OA showed increased ORs for angina and CHF in both men and women, and for MI in women. ORs (95% CI) for men and women, respectively, were 1.08 (0.91 to 1.28) and 1.49 (1.28 to 1.75) for MI, 1.76 (1.43 to 2.17) and 1.84 (1.59 to 2.14) for angina, 1.50 (1.13 to 1.97) and 1.81 (1.49 to 2.21) for CHF, and 1.08 (0.83 to 1.40) and 1.13 (0.93 to 1.37) for stroke.
Conclusions
Prevalent OA was associated with self-reported heart disease, particularly angina, and CHF in both men and women, after controlling for established risk factors for these conditions. This study provides a rationale for further investigation of the association between OA and heart disease in longitudinal studies for investigating possible biological and behavioural mechanisms.
doi:10.1136/bmjopen-2013-002624
PMCID: PMC3657665  PMID: 23674445
Epidemiology
11.  The Cost-Effectiveness and Value of Information of Three Influenza Vaccination Dosing Strategies for Individuals with Human Immunodeficiency Virus 
PLoS ONE  2011;6(12):e27059.
Background
Influenza vaccine immunogenicity is diminished in patients living with HIV/AIDS. We evaluated the cost-effectiveness and expected value of perfect information (EVPI) of three alternative influenza vaccine dosing strategies intended to increase immunogenicity in those patients.
Methods
A randomized, multi-centered, controlled, vaccine trial was conducted at 12 CIHR Canadian HIV Trials Network sites. Three dosing strategies with seasonal, inactivated trivalent, non-adjuvanted intramuscular vaccine were used in HIV infected adults: two standard doses over 28 days (Strategy A), two double doses over 28 days (Strategy B) and a single standard dose of influenza vaccine (Strategy C), administered prior to the 2008 influenza season. The comparator in our analysis was practice in the previous year, in which 82.8% of HIV/AIDS received standard-dose vaccination (Strategy D). A Markov cohort model was developed to estimate the monthly probability of Influenza-like Illness (ILI) over one influenza season. Costs and quality-adjusted life years, extrapolated to the lifetime of the hypothetical study cohorts, were estimated in calculating incremental cost-effectiveness ratios (ICER) and EVPI in conducting further research.
Results
298 patients with median CD4 of 470 cells/µl and 76% with viral load suppression were randomized. Strategy C was the most cost-effective strategy for the overall trial population and for suppressed and unsuppressed individuals. Mean ICERs for Strategy A for unsuppressed patients could also be considered cost-effective. The level of uncertainty regarding the decision to implement strategy A versus C for unsuppressed individuals was high. The maximum acceptable cost of reducing decision uncertainty in implementing strategy A for individuals with unsuppressed pVL was $418,000 - below the cost of conducting a larger-scale trial.
Conclusion
Our results do not support a policy to implement increased antigen dose or booster dosing strategies with seasonal, inactivated trivalent, non-adjuvanted intramuscular vaccine for individuals with HIV in Canada.
Trial Registration
ClinicalTrials.gov NCT00764998.
doi:10.1371/journal.pone.0027059
PMCID: PMC3232195  PMID: 22162988
12.  Validity of the work productivity and activity impairment questionnaire - general health version in patients with rheumatoid arthritis 
Arthritis Research & Therapy  2010;12(5):R177.
Introduction
The Work Productivity and Activity Impairment (WPAI) questionnaire is a well validated instrument to measure impairments in work and activities. However, its validation among patients with rheumatoid arthritis (RA) has not been well established. The present study's purpose is to evaluate the construct validity of the WPAI-general health version among RA patients and its ability to differentiate between RA patients with varying health status.
Methods
Patients who were enrolled in the Early Rheumatoid Arthritis Network cohort and were employed at their most recent follow-up were recruited into this sub-study. A questionnaire battery incorporating the WPAI was administered along with a number of health outcomes including the Multidimensional Health Assessment Questionnaire, fatigue and patient assessment of disease activity. The construct validity of the WPAI was tested by the correlations between the WPAI and the health outcomes and other measures of productivity. Student's t tests were used to identify whether the WPAI outcomes differed between the two levels of heath status based on the median of health outcomes.
Results
A total of 150 patients completed the WPAI questionnaire. The average age was 52 years old and the disease duration was 37.5 months since the first rheumatology visit. Of the 137 patients who were working for pay, 26 reported missing work in the past week due to their health problem, accounting for 45.5% of their working time (absenteeism). While 123 patients were working, 24% of their work was impaired due to their health problem (presenteeism). In addition, 33% of the patients' regular daily activities (activity impairment) had been prevented due to their health problems. There were moderate correlations between the WPAI absenteeism and function, pain, fatigue, and disease severity (r = 0.34 to 0.39). The WPAI presenteeism and activity impairment were strongly correlated with the health outcomes (0.67 to 0.77). Patients with more severe disease status (for example, low/high functional disability by median) had significantly higher absenteeism (4%/15%), presenteeism (15%/39%), and activity impairment (19%/53%) than those with less severe disease status.
Conclusions
The WPAI is a valid questionnaire for assessing impairments in paid work and activities in RA patients and for measuring the relative differences between RA patients with different health status.
doi:10.1186/ar3141
PMCID: PMC2991008  PMID: 20860837
13.  The incidence of co-morbidities related to obesity and overweight: A systematic review and meta-analysis 
BMC Public Health  2009;9:88.
Background
Overweight and obese persons are at risk of a number of medical conditions which can lead to further morbidity and mortality. The primary objective of this study is to provide an estimate of the incidence of each co-morbidity related to obesity and overweight using a meta-analysis.
Methods
A literature search for the twenty co-morbidities identified in a preliminary search was conducted in Medline and Embase (Jan 2007). Studies meeting the inclusion criteria (prospective cohort studies of sufficient size reporting risk estimate based on the incidence of disease) were extracted. Study-specific unadjusted relative risks (RRs) on the log scale comparing overweight with normal and obese with normal were weighted by the inverse of their corresponding variances to obtain a pooled RR with 95% confidence intervals (CI).
Results
A total of 89 relevant studies were identified. The review found evidence for 18 co-morbidities which met the inclusion criteria. The meta-analysis determined statistically significant associations for overweight with the incidence of type II diabetes, all cancers except esophageal (female), pancreatic and prostate cancer, all cardiovascular diseases (except congestive heart failure), asthma, gallbladder disease, osteoarthritis and chronic back pain. We noted the strongest association between overweight defined by body mass index (BMI) and the incidence of type II diabetes in females (RR = 3.92 (95% CI: 3.10–4.97)). Statistically significant associations with obesity were found with the incidence of type II diabetes, all cancers except esophageal and prostate cancer, all cardiovascular diseases, asthma, gallbladder disease, osteoarthritis and chronic back pain. Obesity defined by BMI was also most strongly associated with the incidence of type II diabetes in females (12.41 (9.03–17.06)).
Conclusion
Both overweight and obesity are associated with the incidence of multiple co-morbidities including type II diabetes, cancer and cardiovascular diseases. Maintenance of a healthy weight could be important in the prevention of the large disease burden in the future. Further studies are needed to explore the biological mechanisms that link overweight and obesity with these co-morbidities.
doi:10.1186/1471-2458-9-88
PMCID: PMC2667420  PMID: 19320986
14.  Impact of welfare cheque issue days on a service for those intoxicated in public 
In British Columbia (BC), the Ministry of Human Resources issues welfare cheques to eligible recipients monthly on the last Wednesday of each month. Previous studies have indicated that there are significant increases in hospital admission, ED admission, 911 calls and deaths shortly after the distribution of the monthly welfare cheques. The objective of this analysis was to rigorously examine the impact of welfare cheque issue dates on admission to the Sobering Unit (SU), a service for the publicly intoxicated, in Vancouver, Canada. Data on 1234 consecutive admissions to the SU over a 7-month period were assessed, and the average number of daily admissions on each of the 7 days of the welfare cheque issue week and similar weekdays in other weeks were compared. A Wilcoxon rank-sum test was performed for the comparisons. Our results showed that there were significant increases in the number of admissions on the 3 days starting with "Welfare Wednesday" compared to the similar weekdays in other weeks (Welfare Wednesday vs. other Wednesdays: 8.7 vs. 5.1, p = 0.02; Welfare Thursdays vs. other Thursdays: 9.6 vs. 5.3, p = 0.02; Welfare Fridays vs. other Fridays: 8.6 vs. 5.7, p = 0.04). The demonstrated impact of welfare cheque issue dates is an important consideration for the re-design, staffing and resource allocation of services for withdrawal management and potentially for other services offered to this population.
doi:10.1186/1477-7517-4-12
PMCID: PMC1876222  PMID: 17462093
15.  Highly active antiretroviral therapy and hospital readmission: comparison of a matched cohort 
Background
Despite the known efficacy of highly active antiretroviral therapy (HAART), a large proportion of potentially-eligible HIV-infected patients do not access, and may stand to benefit from this treatment. In order to quantify these benefits in terms of reductions in hospitalizations and hospitalization costs, we sought to determine the impact of HAART on hospital readmission among HIV-infected patients hospitalized at St. Paul's Hospital (SPH) in Vancouver, BC, Canada.
Methods
All patients admitted to a specialized HIV/AIDS ward at SPH (Apr. 1997 – Oct. 2002) were selected and classified as being on HAART or not on HAART based upon their initial admission. Patients were then matched by their propensity scores, which were calculated based on patients' sociodemographics such as age, gender, injection drug use (IDU) status, and AIDS indication, and followed up for one year. Multivariate logistic regression was used to estimate the difference in the odds of hospital readmission between patients on and not on HAART.
Results
Out of a total 1084 patients admitted to the HIV/AIDS ward between 1997 and 2002, 662 were matched according to their propensity score; 331 patients each on and not on HAART. Multivariate logistic regression revealed that patients on HAART had lower odds of AIDS hospital readmission (OR, 0.61; 95% CI, 0.42 – 0.89) compared to patients not on HAART. Odds of readmission among patients on HAART were also significantly lower for non-IDU related readmission (OR, 0.73; 95% CI, 0.53 – 0.99) and overall readmission (OR, 0.72; 95% CI, 0.53 – 0.98).
Conclusion
Propensity score matching allowed us to reliably estimate the association between exposure (on or not on HAART) and outcome (readmitted to hospital). We found that HIV-infected patients who were potentially eligible for, but not on HAART had higher odds of being readmitted to hospital compared to those on HAART. Given the low level of uptake (31%) of HAART observed in our pre-matched hospitalized cohort, a large potential to achieve clinical benefits, reduce hospitalization costs and possibly slow disease progression from improved HAART uptake still exists.
doi:10.1186/1471-2334-6-146
PMCID: PMC1617096  PMID: 17022826
16.  Assessment of health-related quality of life in arthritis: conceptualization and development of five item banks using item response theory 
Background
Modern psychometric methods based on item response theory (IRT) can be used to develop adaptive measures of health-related quality of life (HRQL). Adaptive assessment requires an item bank for each domain of HRQL. The purpose of this study was to develop item banks for five domains of HRQL relevant to arthritis.
Methods
About 1,400 items were drawn from published questionnaires or developed from focus groups and individual interviews and classified into 19 domains of HRQL. We selected the following 5 domains relevant to arthritis and related conditions: Daily Activities, Walking, Handling Objects, Pain or Discomfort, and Feelings. Based on conceptual criteria and pilot testing, 219 items were selected for further testing. A questionnaire was mailed to patients from two hospital-based clinics and a stratified random community sample. Dimensionality of the domains was assessed through factor analysis. Items were analyzed with the Generalized Partial Credit Model as implemented in Parscale. We used graphical methods and a chi-square test to assess item fit. Differential item functioning was investigated using logistic regression.
Results
Data were obtained from 888 individuals with arthritis. The five domains were sufficiently unidimensional for an IRT-based analysis. Thirty-one items were deleted due to lack of fit or differential item functioning. Daily Activities had the narrowest range for the item location parameter (-2.24 to 0.55) and Handling Objects had the widest range (-1.70 to 2.27). The mean (median) slope parameter for the items ranged from 1.15 (1.07) in Feelings to 1.73 (1.75) in Walking. The final item banks are comprised of 31–45 items each.
Conclusion
We have developed IRT-based item banks to measure HRQL in 5 domains relevant to arthritis. The items in the final item banks provide adequate psychometric information for a wide range of functional levels in each domain.
doi:10.1186/1477-7525-4-33
PMCID: PMC1550394  PMID: 16749932
17.  Do visual analogue scale (VAS) derived standard gamble (SG) utilities agree with Health Utilities Index utilities? A comparison of patient and community preferences for health status in rheumatoid arthritis patients 
Background
Assessment of Health Related Quality of Life (HRQL) has become increasingly important and various direct and indirect methods and instruments have been devised to measure it. In direct methods such as Visual Analog Scale (VAS) and Standard Gamble (SG), respondent both assesses and values health states therefore the final score reflects patient's preferences. In indirect methods such as multi-attribute health status classification systems, the patient provides the assessment of a health state and then a multi-attribute utility function is used for evaluation of the health state. Because these functions have been estimated using valuations of general population, the final score reflects community's preferences. The objective of this study is to assess the agreement between community preferences derived from the Health Utilities Index Mark 2 (HUI2) and Mark 3 (HUI3) systems, and patient preferences.
Methods
Visual analog scale (VAS) and HUI scores were obtained from a sample of 320 rheumatoid arthritis patients. VAS scores were adjusted for end-aversion bias and transformed to standard gamble (SG) utility scores using 8 different power conversion formulas reported in other studies. Individual level agreement between SG utilities and HUI2 and HUI3 utilities was assessed using the intraclass correlation coefficient (ICC). Group level agreement was assessed by comparing group means using the paired t-test.
Results
After examining all 8 different SG estimates, the ICC (95% confidence interval) between SG and HUI2 utilities ranged from 0.45 (0.36 to 0.54) to 0.55 (0.47 to 0.62). The ICC between SG and HUI3 utilities ranged from 0.45 (0.35 to 0.53) to 0.57 (0.49 to 0.64). The mean differences between SG and HUI2 utilities ranged from 0.10 (0.08 to 0.12) to 0.22 (0.20 to 0.24). The mean differences between SG and HUI3 utilities ranged from 0.18 (0.16 to 0.2) to 0.28 (0.26 to 0.3).
Conclusion
At the individual level, patient and community preferences show moderate to strong agreement, but at the group level they have clinically important and statistically significant differences. Using different sources of preference might alter clinical and policy decisions that are based on methods that incorporate HRQL assessment. VAS-derived utility scores are not good substitutes for HUI scores.
doi:10.1186/1477-7525-4-25
PMCID: PMC1553436  PMID: 16626489
18.  When patients have to pay a share of drug costs: effects on frequency of physician visits, hospital admissions and filling of prescriptions 
Background
Previous research has shown that patient cost-sharing leads to a reduction in overall health resource utilization. However, in Canada, where health care is provided free of charge except for prescription drugs, the converse may be true. We investigated the effect of prescription drug cost-sharing on overall health care utilization among elderly patients with rheumatoid arthritis.
Methods
Elderly patients (≥ 65 years) were selected from a population-based cohort with rheumatoid arthritis. Those who had paid the maximum amount of dispensing fees ($200) for the calendar year (from 1997 to 2000) were included in the analysis for that year. We defined the period during which the annual maximum co-payment had not been reached as the “cost-sharing period” and the one beyond which the annual maximum co-papyment had been reached as the “free period.” We compared health services utilization patterns between these periods during the 4 study years, including the number of hospital admissions, the number of physician visits, the number of prescriptions filled and the number of prescriptions per physician visit.
Results
Overall, 2968 elderly patients reached the annual maximum cost-sharing amount at least once during the study periods. Across the 4 years, there were 0.38 more physician visits per month (p < 0.001), 0.50 fewer prescriptions filled per month (p = 0.001) and 0.52 fewer prescriptions filled per physician visit (p < 0.001) during the cost-sharing period than during the free period. Among patients who were admitted to the hospital at least once, there were 0.013 more admissions per month during the cost-sharing period than during the free period (p = 0.03).
Interpretation
In a predominantly publicly funded health care system, the implementation of cost-containment policies such as prescription drug cost-sharing may have the unintended effect of increasing overall health utilization among elderly patients with rheumatoid arthritis.
doi:10.1503/cmaj.045146
PMCID: PMC1283500  PMID: 16301701
19.  National pharmacare: a dog's tale 
doi:10.1503/cmaj.1020352
PMCID: PMC516187  PMID: 15367455
20.  Safety and efficiency of emergency department assessment of chest discomfort 
Background
Most Canadian emergency departments use an unstructured, individualized approach to patients with chest pain, without data to support the safety and efficiency of this practice. We sought to determine the proportions of patients with chest discomfort in emergency departments who either had acute coronary syndrome (ACS) and were inappropriately discharged from the emergency department or did not have ACS and were held for investigation.
Methods
Consecutive consenting patients aged 25 years or older presenting with chest discomfort to 2 urban tertiary care emergency departments between June 2000 and April 2001 were prospectively enrolled unless they had a terminal illness, an obvious traumatic cause, a radiographically identifiable cause, severe communication problems or no fixed address in British Columbia or they would not be available for follow-up by telephone. At 30 days we assigned predefined explicit outcome diagnoses: definite ACS (acute myocardial infarction [AMI] or definite unstable angina) or no ACS.
Results
Of 1819 patients, 241 (13.2%) were assigned a 30-day diagnosis of AMI and 157 (8.6%), definite unstable angina. Of these 398 patients, 21 (5.3%) were discharged from the emergency department without a diagnosis of ACS and without plans for further investigation. The clinical sensitivity for detecting ACS was 94.7% (95% confidence interval [CI] 92.5%– 96.9%) and the specificity 73.8% (95% CI 71.5%– 76.0%). Of the patients without ACS or an adverse event, 71.1% were admitted to hospital or held in the emergency department for more than 3 hours.
Interpretation
The current individualized approach to evaluation and disposition of patients with chest discomfort in 2 Canadian tertiary care emergency departments misses 5.3% of cases of ACS while consuming considerable health care resources for patients without coronary disease. Opportunities exist to improve both safety and efficiency.
doi:10.1503/cmaj.1031315
PMCID: PMC419767  PMID: 15184334
21.  Predictors of Early Hospital Readmission in HIV-infected Patients with Pneumonia 
OBJECTIVE
Although hospitalization patterns have been studied, little is known about hospital readmission among HIV-infected patients in the era of highly active antiretroviral therapy. We explored the risk factors for early readmission to a tertiary care inner-city hospital among HIV-infected patients with pneumonia in Vancouver, Canada.
DESIGN
Case-control study.
SETTING
Tertiary care, university-affiliated, inner-city hospital.
PARTICIPANTS
All HIV-infected patients who were hospitalized with Pneumocystis carinii pneumonia (PCP) or bacterial pneumonia (BP) between January 1997 and December 2000. Case patients included those who had early readmissions, defined as being readmitted within 2 weeks of discharge (N = 131). Control patients were randomly selected HIV-infected patients admitted during the study period who were not readmitted within 2 weeks of discharge (N = 131), matched to the cases by proportion of PCP to BP.
MEASUREMENTS
Sociodemographic, HIV risk category, and clinical data were compared using χ2 test for categorical variables, and the Wilcoxon rank-sum test was used for continuous variables. Multivariable logistic regression was performed to determine the factors independently associated with early readmission. We also reviewed the medical records of 132 patients admitted to the HIV/AIDS ward during the study period and collected more detailed clinical data for a subanalysis.
MAIN RESULTS
Patients were at significantly increased odds of early readmission if they left the hospital against medical advice (AMA) (adjusted odds ratio [OR], 4.26; 95% confidence interval [95% CI], 2.13 to 8.55), lived in the poorest urban neighborhood (OR, 2.03; 95% CI, 1.09 to 3.77), were hospitalized in summer season (May though October, OR, 2.36; 95% CI, 1.36 to 4.10), or had been admitted in the preceding 6 months (OR, 2.55; 95% CI, 1.46 to 4.47). Gender, age, history of AIDS-defining illness, and injection drug use status were not significantly associated with early readmission.
CONCLUSIONS
Predictors of early readmission of HIV-infected patients with pneumonia included: leaving hospital AMA, living in the poorest urban neighborhood, being hospitalized in the preceding 6 months and during the summer months. Interventions involving social work may address some of the underlying reasons why these patients leave hospital AMA and should be further studied.
doi:10.1046/j.1525-1497.2003.20720.x
PMCID: PMC1494845  PMID: 12709090
case-control; hospital readmission; HIV; AIDS; bacterial pneumonia; PCP; antiretroviral therapy
22.  Impact of supply-side policies for control of illicit drugs in the face of the AIDS and overdose epidemics: investigation of a massive heroin seizure 
Background
More than 93% of the nearly $500 million spent annually on Canada's drug strategy goes toward efforts to reduce the illicit drug supply. However, little is known about the effectiveness of this strategy. On Sept. 2, 2000, Canadian police seized approximately 100 kg of heroin in one of the nation's largest-ever seizures of this drug. An ongoing prospective cohort study of injection drug users afforded an opportunity to evaluate the impact of this seizure.
Methods
The Vancouver Injection Drug User Study is a prospective cohort study of injection drug users that began in 1996. The present study relied primarily on data acquired from participants who were seen during the 30-day periods immediately before and after the seizure. We compared drug use and behavioural characteristics, heroin and cocaine prices, and participants' reports of whether law enforcement had affected their source of drugs or the types of drugs available on the street, as well as overdoses, in these 2 periods.
Results
The 138 participants seen before the seizure were similar to the 123 participants seen after the seizure with respect to age, sex, ethnic background, education, HIV serostatus, neighbourhood residence, instability of housing, employment status, use of methadone maintenance therapy and all other measured potential confounders (all p > 0.10). We found no difference in the extent to which participants in the 2 groups reported daily use of heroin, frequency of nonfatal overdoses, or whether law enforcement had affected their source of drugs or the types of drugs available on the street (all p > 0.10). Although we detected no difference in the price of cocaine, the median reported price of heroin went down after the seizure (p = 0.034), which suggests that other shipments compensated for the seizure. External evaluations of deaths from overdoses and heroin purity indicated that the seizure had no impact, nor was any impact seen when the periods of analysis were extended.
Interpretation
The massive heroin seizure appeared to have no measurable public health benefit. Closer scrutiny of enforcement efforts is warranted to ensure that resources are delivered to the most efficient and cost-effective public health programs.
PMCID: PMC140425  PMID: 12538544
23.  Economic evaluation of the benefits of reducing acute cardiorespiratory morbidity associated with air pollution 
Background
Few assessments of the costs and benefits of reducing acute cardiorespiratory morbidity related to air pollution have employed a comprehensive, explicit approach to capturing the full societal value of reduced morbidity.
Methods
We used empirical data on the duration and severity of episodes of cardiorespiratory disease as inputs to complementary models of cost of treatment, lost productivity, and willingness to pay to avoid acute cardiorespiratory morbidity outcomes linked to air pollution in epidemiological studies. A Monte Carlo estimation procedure was utilized to propagate uncertainty in key inputs and model parameters.
Results
Valuation estimates ranged from $13 (1997, Canadian) (95% confidence interval, $0–28) for avoidance of an acute respiratory symptom day to $5,200 ($4,000–$6,400) for avoidance of a cardiac hospital admission. Cost of treatment accounted for the majority of the overall value of cardiac and respiratory hospital admissions as well as cardiac emergency department visits, while lost productivity generally represented a small proportion of overall value. Valuation estimates for days of restricted activity, asthma symptoms and acute respiratory symptoms were sensitive to alternative assumptions about level of activity restriction. As an example of the application of these values, we estimated that the observed decrease in particulate sulfate concentrations in Toronto between 1984 and 1999 resulted in annual benefits of $1.4 million (95% confidence interval $0.91–1.8 million) in relation to reduced emergency department visits and hospital admissions for cardiorespiratory disease.
Conclusion
Our approach to estimating the value of avoiding a range of acute morbidity effects of air pollution addresses a number of limitations of the current literature, and is applicable to future assessments of the benefits of improving air quality.
doi:10.1186/1476-069X-1-7
PMCID: PMC149396  PMID: 12537591
24.  Leaving hospital against medical advice among HIV-positive patients 
Background
Hospital discharge against medical advice, especially among substance-abusing populations, is a frustrating problem for health care pro-viders. Because of the high prevalence of injection drug use among HIV- positive patients admitted to hospital in Vancouver, we explored the factors associated with leaving hospital against medical advice in this population.
Methods
We reviewed records for all HIV/AIDS patients admitted to St. Paul's Hospital, Vancouver, between Apr. 1, 1997, and Mar. 1, 1999. After identifying the first (“index”) admission during this period, we followed the patients' records for 1 year. Multivariate models were applied to identify the determinants of discharge against medical advice and to estimate the impact of such discharge on readmission rate, readmission frequency and length of stay in hospital.
Results
Of 981 index admissions among HIV/AIDS patients, 125 (13%) of the patients left the hospital against medical advice. Departure on the day on which welfare cheques were issued and a history of injection drug use were significant predictors of leaving against medical advice. After adjusting for sex, age, severity of illness, injection drug use and homelessness, we found that patients leaving against medical advice were readmitted more frequently than those who were formally discharged (frequency ratio 1.25, 95% confidence interval [CI] 1.11–1.42), were more likely to be readmitted with a related diagnosis within 30 days (odds ratio 5.00, 95% CI 3.04–8.24) and had significantly longer lengths of stay in the follow-up period.
Interpretation
Discharge against medical advice among HIV-positive patients was associated with frequent readmissions with the same diagnosis. Preventing such discharges is likely to benefit patients (by improving their health status) and the health care system (by reducing unnecessary readmissions).
PMCID: PMC122025  PMID: 12358196
25.  Hospital utilization and costs in a cohort of injection drug users 
Background
Many injection drug users (IDUs) seek care at emergency departments and some require hospital admission because of late presentation in the course of their illness. We determined the predictors of frequent emergency department visits and hospital admissions among community-based IDUs and estimated the incremental hospital utilization costs incurred by IDUs with early HIV infection relative to costs incurred by HIV-negative IDUs.
Methods
The Vancouver Injection Drug User Study (VIDUS) is a prospective cohort study involving IDUs that began in 1996. Our analyses were restricted to the 598 participants who gave informed consent for our study. We used the participants' responses to the baseline VIDUS questionnaire and, from medical records at St. Paul's Hospital, Vancouver, we collected detailed information about the frequency of emergency department visits, hospital admissions and the primary diagnosis for all visits or hospital stays between May 1, 1996, and Aug. 31, 1999. The incremental difference in hospital utilization costs by HIV status was estimated, based on 105 admissions in a subgroup of 64 participants.
Results
A total of 440 (73.6%) of the 598 IDUs made 2763 visits to the emergency department at St. Paul's Hospital during the study period. Of these 440, 265 (60.2%) made frequent visits (3 or more). The following factors were associated with frequent use: HIV-positive status (seroprevalent: adjusted odds ratio [OR] 1.7, 95% confidence interval [CI] 1.2–2.6; seroconverted during study period: adjusted OR 3.0, 95% CI 1.6–5.7); more than 4 injections daily (adjusted OR 1.5, 95% CI 1.1–2.1); cocaine use more frequent than use of other drugs (adjusted OR 2.0, 95% CI 1.2–3.6); and unstable housing (adjusted OR 1.5, 95% CI 1.1–2.2). During the study period 210 of the participants were admitted to hospital 495 times; 118 (56.2%) of them were admitted frequently (2 or more admissions). The 2 most common reasons for admission were pneumonia (132 admissions among 79 patients) and soft-tissue infections (cellulitis and skin abscess) (90 admissions among 59 patients). The following factors were independently associated with frequent hospital admissions: HIV-positive status (seroprevalent: adjusted OR 5.4, 95% CI 3.4–8.6; seroconverted during study period: adjusted OR 2.9, 95% CI 1.4–6.0); and female sex (adjusted OR 1.8, 95% CI 1.1–3.1). The incremental hospital utilization costs incurred by HIV-positive IDUs relative to the costs incurred by HIV-negative IDUs were $1752 per year.
Interpretation
Hospital utilization was significantly higher among community-based IDUs with early HIV disease than among those who were HIV negative. Much of the hospital use was related to complications of injection drug use and may be reduced with the establishment of programs that integrate harm reduction strategies with primary care and addiction treatment.
PMCID: PMC81365  PMID: 11531049

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