Jacek A Kopec

University of British Columbia - Vancouver, Vancouver, British Columbia, Canada

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Publications (148)524.53 Total impact

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    ABSTRACT: 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.
    International Journal of Rheumatology 11/2014; 2014:620920. DOI:10.1155/2014/620920
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    ABSTRACT: Identifying persons with early rheumatoid arthritis (RA) is a major challenge. The role of the Internet in making decisions about seeking care has not been studied. We developed a method for early diagnosis and referral using the Arthritis Foundation's website. A person with less than 3 months of joint pain symptom who has not yet sought medical attention was screened. Prescreened persons are linked to a self-scoring questionnaire and get a "likelihood" of RA statement. If "likely," the person is offered a free evaluation and biomarker testing performed by Quest Diagnostics. The system available only to Massachusetts's residents yielded a small steady flow of screen-positive individuals. Over 21 months, 43,244 persons took the Arthritis Foundation website prescreening questionnaire; 196 were from Massachusetts and 60 took the self-scoring algorithm. Of the 48 who screened positive, 29 set up an appointment for a free evaluation, but six never came in. Twenty-four subjects were evaluated and diagnosed independently by three rheumatologists. One met the 1987 American College of Rheumatology (ACR) criteria for RA and two met the 2010 ACR/EULAR RA criteria. The 24 examined individuals were contacted at a minimum of 1 year and asked to redo the case-finding questionnaire and asked about their health resource utilization during the interval. Seventeen of the 24 subjects responded, and 10 had seen a health professional. Three of the 17 had a diagnosis of RA; all were on at least methotrexate. Internet case finding was useful in identifying new potential RA cases. The system's performance characteristics are theoretically limited only by the number of study sites available. However, the major barrier may be that seeing a health professional is not a priority for many individuals with early symptoms.
    Clinical Rheumatology 10/2014; DOI:10.1007/s10067-014-2796-7 · 1.77 Impact Factor
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    ABSTRACT: Gestational Diabetes Mellitus (GDM) is a common health problem among pregnant women and may be associated with distress.
    International Journal of Behavioral Medicine 08/2014; DOI:10.1007/s12529-014-9428-0 · 2.63 Impact Factor
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    ABSTRACT: Objective. To evaluate the validity (accuracy) and reliability of 2 commonly used clinical methods, 1 indirect (lifts) and 1 direct (tape measure), for assessment of leg length discrepancy (LLD) in comparison to radiograph. Methods. Twenty subjects suspected of having LLD participated in this study. Two clinical methods, 1 direct using a tape measure and 1 indirect using lifts, were standardized and carried out by 4 examiners. Difference in height of the femoral heads on standing pelvic radiograph was measured and served as the gold standard. Results. The intraclass correlation coefficient assessing interobserver reliability was 0.737 for lifts and 0.477 for tape measure. The remainder of the analysis is based on the average of the measurements by the 4 examiners. Pearson correlation coefficients were 0.93 for the lifts and 0.75 for the tape measure method. Paired sample t tests showed difference in means of 2 mm (p = 0.051) for lifts and -5 mm (p = 0.007) for tape measure compared with radiograph. Sensitivity and specificity were 55% and 89% for lifts and 45% and 56% for tape measure, respectively, using > 5 mm as the definition for LLD. The wrong leg was identified as being shorter in 1 out of 20 subjects using lifts versus 7 out of 20 using tape measure. Conclusion. The indirect standing method of LLD measurement using lifts had superior validity, interobserver reliability, and specificity in comparison with radiograph over the direct supine method using tape measure. Both clinical methods underestimated LLD compared with radiograph.
    The Journal of Rheumatology 07/2014; 41(8). DOI:10.3899/jrheum.131089 · 3.17 Impact Factor
  • Annals of the Rheumatic Diseases 06/2014; 73(Suppl 2):259-259. DOI:10.1136/annrheumdis-2014-eular.4840 · 9.27 Impact Factor
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    ABSTRACT: To calculate the incidence rates of osteoarthritis (OA) and to describe the changes in incidence using 18 years of administrative health records. We analyzed visits to health professionals and hospital admission records in a random sample (n = 640,000) from British Columbia, Canada, from 1991/1992 through 2008/2009. OA was defined in 2 ways: (1) at least 1 physician diagnosis or 1 hospital admission; and (2) at least 2 physician diagnoses in 2 years or 1 hospital admission. Crude and age-standardized rates were calculated, and the annual relative changes were estimated from the Poisson regression models. In 2008/2009, the overall crude incidence rate (95% CI) of OA using definition 1 was 14.6 (14.0-14.8); [12.5 (12.0-13.0) among men and 16.3 (15.8-16.8) among women] per 1000 person-years. The rates were lower by about 44% under definition 2. For the period 2000/2001-2008/2009, crude incidence rates based on definition 1 varied from 11.8 to 14.2 per 1000 person-years for men, and from 15.7 to 18.5 for women. Annually, on average, crude rates rose by about 2.5-3.3% for both men and women. The age-adjusted rates increased by 0.6-0.8% among men and showed no trend among women. Our study generated updated incidence rates of administrative OA for the Province of British Columbia. Physician-diagnosed overall incidence rates of OA varied with the case definitions used; however, trends were similar in both case definitions. Age-adjusted rates among men increased slightly during the period 2000/2001-2008/2009. These findings have implications for projecting future prevalence and costs of OA.
    The Journal of Rheumatology 04/2014; 41(6). DOI:10.3899/jrheum.131011 · 3.17 Impact Factor
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    ABSTRACT: Purpose To assess the association between subchondral sclerosis detected at baseline with MRI and cartilage loss over time in the same region of the knee in a cohort of subjects with knee pain. Methods 163 subjects with knee pain participated in a longitudinal study to assess knee osteoarthritis progression. Subjects received baseline knee radiographs as well as baseline and 3-year follow-up MRI examinations. Baseline subchondral sclerosis and bone marrow lesions (BMLs) were scored semiquantitatively on MRI in each region from 0 to 3. Cartilage morphology at baseline and follow-up was scored semiquantitatively from 0 to 4. The association between baseline subchondral sclerosis and cartilage loss in the same region of the knee was evaluated using logistic regression, adjusting the results for age, gender, body mass index, and the presence of concomitant BMLs. Results The prevalence of subchondral sclerosis detected by MRI in the regions of the knee varied between 1.6% (trochlea) and 17% (medial tibia). The occurrence of cartilage loss over time in regions varied between 6% (lateral tibia) and 13.1% (medial femur). The prevalence of radiographically-detected subchondral sclerosis in compartments varied from 2.9% (patellofemoral) to 14.2% (medial tibiofemoral). In logistic regression models, there were no significant associations between baseline subchondral sclerosis detected by MRI and cartilage loss in the same region of the knee. Conclusion Baseline subchondral sclerosis as detected by MRI did not increase the risk of cartilage loss over time.
    Osteoarthritis and Cartilage 04/2014; DOI:10.1016/j.joca.2014.01.006 · 4.66 Impact Factor
  • Osteoarthritis and Cartilage 04/2014; 22:S270-S271. DOI:10.1016/j.joca.2014.02.508 · 4.66 Impact Factor
  • Annals of the Rheumatic Diseases 01/2014; 72(Suppl 3):A695-A695. DOI:10.1136/annrheumdis-2013-eular.2056 · 9.27 Impact Factor
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    ABSTRACT: Objective To determine the risk of cardiovascular disease (CVD) among osteoarthritis (OA) patients using population-based administrative data from British Columbia, Canada. Methods The medical history of a random sample of 600,000 individuals from 1991-2009 was analyzed. A total of 12,745 OA cases and up to 3 non-OA individuals matched by age, sex, and year of diagnosis were followed for CVD events. Cox proportional hazards and Poisson regression models were used to estimate the relative risks (RRs) of CVD, myocardial infarction, ischemic heart disease (IHD), congestive heart failure (CHF), and stroke after adjusting for available sociodemographic and medical factors. ResultsOA was an independent predictor of CVD. The adjusted RRs were 1.15 (95% confidence interval [95% CI] 1.04-1.27), 1.26 (95% CI 1.13-1.42), and 1.17 (95% CI 1.07-1.26) among older men, younger women, and older women, respectively. Analyses were stratified by age and sex due to statistically significant interactions between OA and age and sex. RRs among older men, younger women, and older women were 1.33 (95% CI 1.11-1.62), 1.66 (95% CI 1.37-2.01), and 1.45 (95% CI 1.22-1.72) for IHD, respectively, and 1.25 (95% CI 1.02-1.54), 1.29 (95% CI 1.00-1.68), and 1.20 (95% CI 1.03-1.39) for CHF, respectively. Compared to non-OA individuals, OA cases who underwent total joint replacements had a 26% increased risk of CVD. Conclusion This prospective longitudinal study suggests that OA is associated with an increased risk of CVD. Older men and adult women with OA had a higher risk of CVD, particularly IHD and CHF. Further studies are needed to confirm these results and to elucidate the potential biologic mechanisms.
    12/2013; 65(12). DOI:10.1002/acr.22092
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    ABSTRACT: Abstract Background: Recent research has identified younger women as an "at-risk" population with rising prevalence of cardiac risk factors and excess mortality risk following acute myocardial infarction (AMI). However, population-based data on trends in AMI hospitalization and early mortality post AMI among younger adults is scarce. We, therefore, aimed to provide a 10-year, descriptive analysis of these trends in a Canadian setting. Methods and Results: We assessed trends and sex differences in AMI hospitalization and 30-day mortality rates using negative binomial and logistic regression, respectively. From 2000 to 2009, there were 70,628 AMI hospitalizations in adults aged ≥20 years, in British Columbia, Canada, with 17.1% of cohort being younger adults ≤55 years. Overall, age-standardized AMI rates (per 100,000 population) declined similarly in men (295.8 to 247.7) and women (152.1 to 128.8) [sex-year interaction p=0.81]. However, these trends differed according to age (age-sex-year interaction p=0.02) with increased rates observed only in younger women (+1.7% per year; p=0.04). The 30-day mortality rates declined similarly for women (19.4% to 13.9%) and men (13.0% to 9.3%) (sex-year interaction p=0.33). Yet, younger women continued to have excess mortality risk, compared with younger men, even in the most recent period [odds ratio: 2008-09=1.61 (95% onfidence interval: 1.25, 2.08)]. Conclusion: While the overall AMI hospitalization and 30-day mortality rates significantly declined in women and men, hospitalization rates in women ≤55 years increased and their excess risk of 30-day mortality persisted. These findings highlight the need to intensify strategies to reduce the incidence of AMI and improve outcomes after AMI in younger women.
    Journal of Women's Health 11/2013; DOI:10.1089/jwh.2013.4507 · 1.90 Impact Factor
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    ABSTRACT: Adaptive tests are increasingly being used to assess health-related quality of life in patients with a variety of medical conditions, including osteoarthritis (OA) of the knee. This approach has recently been used to assess health state utility valuations (HSUV) for use in quality-adjusted life-year calculations. To accurately assess incremental value for money, these tools must be responsive. Therefore, we examined the responsiveness of the Health Utilities Index mark 3 (HUI3) and Paper Adaptive Test-5D (PAT-5DQOL) in a group of patients with knee OA. We used patient-level data from a randomized controlled trial evaluating a pharmacist-initiated multidisciplinary intervention in newly diagnosed patients with knee OA. The mean change for utility scores from baseline to 6 months was calculated, as well as effect size (ES) and standardized response mean (SRM) for the HUI3 and PAT-5DQOL, and generalized additive model plots, using the Western Ontario and McMaster Osteoarthritis index as a reference standard. When patients were assessed based on whether their condition had improved, remained unchanged, or worsened over time, the PAT-5DQOL showed greater responsiveness in patients whose condition had either improved or worsened. ES and SRM were generally small for both instruments. The PAT-5DQOL is more responsive to change over time than the HUI3 in patients with knee OA.
    The Journal of Rheumatology 11/2013; 40(12). DOI:10.3899/jrheum.130176 · 3.17 Impact Factor
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    ABSTRACT: Knee injuries can lead to radiographic osteoarthritis (ROA). Injuries may be "specific" (SI) including ligament or meniscal tears or patellar trauma, or "nonspecific" (NSI). Our objective is to understand the effect of knee NSI on ROA incidence and progression. 163 people (sample-weighted for population representativeness) aged 40+ with history of knee pain had radiographs assessed on Kellgren Lawrence (KL) grade (0/1 collapsed) at baseline and follow-up (median 3.2 years apart). Progression was an increase in KL score. SIs and NSIs were labeled "severe" (walking aid for >=1 week) or "moderate". One model treated SI and NSI as dichotomous (yes/no), and another as trichotomous (none/moderate/severe). Models were adjusted for age, sex, BMI, KL grade and follow-up time. SI/NSI history was none, moderate (7.8/24.4%) or severe (11.0/10.8%). Duration at baseline since SI/NSI ranged from <1 year to several decades (SI/NSI mean 4.6/6.5 years). SI was significantly associated with ROA incidence and progression (odds ratio (OR) = 2.90; 95% CI = 1.04, 8.09), but NSI showed no significant effect (OR = 1.36; 95% CI = 0.61, 3.02). In the trichotomous model, severe SI was significant (OR = 4.35, 95% CI = 1.26, 15.02), while moderate SI was not (OR = 1.51, 95% CI = 0.33, 6.84). NSI showed no effect: moderate OR = 1.51, 95% CI = 0.61, 3.74; severe OR = 0.90, 95% CI = 0.24, 3.40. This study had 80% power to detect an NSI OR of 2.9. We find no evidence that history of NSI affects knee ROA incidence and progression in a population with knee pain, adjusting for SI, age, sex, BMI, KL grade and follow-up time.
    BMC Musculoskeletal Disorders 10/2013; 14(1):309. DOI:10.1186/1471-2474-14-309 · 1.90 Impact Factor
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    ABSTRACT: Waitlists are commonly used in Canada to manage access to surgical procedures such as elective surgical lumbar discectomy (ESLD). The timing of enrollment onto the waitlist is important as this is a proxy measure for the concordance of preferences for surgery between a patient and surgeon. After enrollment, the waiting time to actual surgery extends the duration of preoperative symptoms, which possibly affects the outcome of ESLD. Waiting time also specifically reflects the delay in service delivery imposed by the limited capacity of the health-care system. To determine if a system-imposed delay in treatment, that is, longer waiting time, for ESLD is associated with a higher odds of experiencing residual postoperative pain. Ambidirectional cohort study with 2-year retrospective and 3-year prospective components, conducted at a major tertiary care center serving a metropolitan area in Canada. Patients aged 16 years or older with sciatica because of herniated lumbar disc, confirmed on advanced imaging, were recruited at the time of waitlist enrollment for ESLD. Patients with significant comorbidity or emergency indications for surgery were excluded. Of 391 participants, 291 had complete follow-up information at 6 months postoperatively. Intensity of the predominant symptom (worse of either back or leg pain) was assessed on the 11-point numerical rating scale at waitlist enrollment and 6 months postoperatively. Pain scores were highly skewed and therefore categorized into four ordinal levels defined by quartiles. For the primary analysis, time to surgery from waitlist enrollment was dichotomized based on a predetermined clinically meaningful cut-point of 12 weeks. Ordinal logistic regression was used to compare the odds of experiencing higher pain intensity between wait groups. Control of confounders was achieved using both propensity scores and conventional multivariable modeling. In unadjusted analyses, long-wait patients were 80% more likely than short-wait patients to experience higher ordinal pain intensity at 6 months; unadjusted proportional odds ratio (POR)=1.8 (95% confidence interval [CI], 1.2-2.8). The association held after controlling for all imbalances in measured confounders, with long-wait patients still being 70% more likely to report worse pain; adjusted POR=1.7 (95% CI, 1.0-2.8). A waiting time of 12 weeks or more after waitlist enrollment for ESLD is associated with a modest likelihood of experiencing worse pain at 6 months postoperatively. This result was not because of differences in measured confounders. Future studies are encouraged to identify other, as-of-yet unmeasured, variables that might be associated with both longer waiting times and worse outcomes among ESLD patients. Until then, in jurisdictions where highly constrained access to ESLD is managed through waitlists, the expected waiting time for the operation could be an informative deciding criterion for patients with otherwise unresolved preferences for operative treatment.
    The spine journal: official journal of the North American Spine Society 07/2013; 13(12). DOI:10.1016/j.spinee.2013.05.038 · 2.80 Impact Factor
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    ABSTRACT: Objective To compare the incidence and progression of radiographic osteoarthritis (OA) in the knee and hip among African Americans and whites. Methods Using the joint as the unit of analysis, we analyzed data from the Johnston County Osteoarthritis Project, a population-based prospective cohort study in rural North Carolina. Baseline and followup assessments were 3–13 years apart. Assessments included standard knee and hip radiographs read for Kellgren/Lawrence (K/L) radiographic grade. Weighted analyses controlled for age, sex, body mass index, level of education, and baseline K/L grade; bootstrap methods adjusted for lack of independence between left and right joints. Time-to-event analysis was used to analyze the data. ResultsFor radiographic knee OA, being African American had no association with incidence (adjusted hazard ratio [HRadj] 0.80, 95% confidence interval [95% CI] 0.53–1.22), but had a positive association with progression (HRadj 1.67, 95% CI 1.05–2.67). For radiographic hip OA, African Americans had a significantly lower incidence (HRadj 0.44, 95% CI 0.27–0.71), whereas the association with progression was positive but nonsignificant (HRadj 1.46, 95% CI 0.53–4.01). In sensitivity analyses, the association with hip OA incidence was robust to a wide range of assumptions. Conclusion African Americans are protected against incident hip OA, but may be more susceptible to progressive knee OA.
    06/2013; 65(6). DOI:10.1002/acr.21924
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    ABSTRACT: OBJECTIVES: To develop a paper-and-pencil semi-adaptive test for 5 domains of health-related quality of life (PAT-5D-QOL) based on item response theory (IRT). METHODS: The questionnaire uses items from previously developed item banks for 5 domains: (1) walking, (2) handling objects, (3) daily activities, (4) pain or discomfort, and (5) feelings. For each domain, respondents are initially classified into 4 functional levels. Depending on the level, they are instructed to respond to a different set of 5 additional questions. IRT scores for each domain and overall health utility scores are obtained using a simple spreadsheet. The questions were selected using psychometric and conceptual criteria. The format of the questionnaire was developed through focus groups and cognitive interviews. Feasibility was tested in two population surveys. A simulation study was conducted to compare PAT-5D-QOL with a computerized adaptive test (CAT-5D-QOL) and a fixed questionnaire, developed from the same item banks, in terms of accuracy, bias, precision, and ceiling and floor effects. RESULTS: Close to 90 % of the participants in feasibility studies followed the skip instructions properly. In a simulation study, scores on PAT-5D-QOL for all domains tended to be more accurate, more precise, less biased, and less affected by a ceiling effect than scores on a fixed IRT-based questionnaire of the same length. PAT-5D-QOL was slightly inferior to a fully adaptive instrument. CONCLUSIONS: PAT-5D-QOL is a novel, semi-adaptive, IRT-based measure of health-related quality of life with a broad range of potential applications.
    Quality of Life Research 05/2013; DOI:10.1007/s11136-013-0419-4 · 2.86 Impact Factor
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    ABSTRACT: 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.
    BMJ Open 05/2013; 3(5). DOI:10.1136/bmjopen-2013-002624 · 2.06 Impact Factor
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    The 10th International Congress on SLE: Lupus 2013, Buenos Aires, Argentina; 04/2013
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    Osteoarthritis and Cartilage 04/2013; 21:S161. DOI:10.1016/j.joca.2013.02.343 · 4.66 Impact Factor
  • Osteoarthritis and Cartilage 04/2013; 21:S156-S157. DOI:10.1016/j.joca.2013.02.334 · 4.66 Impact Factor

Publication Stats

3k Citations
524.53 Total Impact Points


  • 2003–2014
    • University of British Columbia - Vancouver
      • • Department of Medicine
      • • School of Population and Public Health
      • • Faculty of Medicine
      Vancouver, British Columbia, Canada
  • 2001–2013
    • Arthritis Research Centre of Canada
      Richmond, British Columbia, Canada
  • 2009
    • Simon Fraser University
      • Department of Statistics and Actuarial Sciences
      Burnaby, British Columbia, Canada
  • 2007
    • University of Pittsburgh
      Pittsburgh, Pennsylvania, United States
  • 2005
    • University of Ottawa
      Ottawa, Ontario, Canada
  • 2004
    • The Arthritis Society
      Toronto, Ontario, Canada
  • 2002–2003
    • Institute for Clinical Evaluative Sciences
      Toronto, Ontario, Canada
  • 1998
    • University of Toronto
      Toronto, Ontario, Canada
  • 1996
    • Sunnybrook Health Sciences Centre
      Toronto, Ontario, Canada
  • 1993
    • McGill University
      • Department of Medicine
      Montréal, Quebec, Canada