M. Mushfiqur Rahman

Epidemiology of gout in women: Fifty-two–year followup of a prospective cohort

OBJECTIVE Despite the recent doubling of the incidence of gout among women and its substantial prevalence particularly in the aging female population, the risk factors for gout among women remain unknown. We undertook this study to evaluate purported risk factors for incident gout among women and to compare them with those among men. METHODS Using prospective data from the Framingham Heart Study, we examined over a 52-year period (1950-2002) the relationship between purported risk factors and the incidence of gout in 2,476 women and 1,951 men. RESULTS We documented 304 incident cases of gout, 104 of them among women. The incidence rates of gout for women per 1,000 person-years according to serum uric acid levels of <5.0, 5.0-5.9, 6.0-6.9, 7.0-7.9, and > or = 8.0 mg/dl were 0.8, 2.5, 4.2, 13.1, and 27.3, respectively (P for trend < 0.0001). The magnitude of this association was lower than that among men (P for interaction = 0.0002). Multivariate relative risks conferred by increasing age (per 5 years), obesity (body mass index > or = 30 kg/m(2)), alcohol intake (> or = 7 ounces of pure alcohol/week), hypertension, and diuretic use were 1.24, 2.74, 3.10, 1.82, and 2.39, respectively (all P < 0.05), for women. CONCLUSION These prospective data with long-term followup provide evidence that higher levels of serum uric acid increase the risk of gout in a graded manner among women, but the rate of increase is lower than that among men. Increasing age, obesity, alcohol consumption, hypertension, and diuretic use were associated with the risk of incident gout among women.

Immediate and past cumulative effects of oral glucocorticoids on the risk of acute myocardial infarction in rheumatoid arthritis: a population-based study

OBJECTIVES To determine the effect of glucocorticoids (GCs) on acute myocardial infarction (MI) risk in patients with RA. METHODS Using administrative health data, we conducted a population-based cohort study of 8384 incident RA cases (1997-2006). Primary exposure was incident GC use. MI events were ascertained using hospitalization and vital statistics data. We used Cox proportional-hazards models and modelled GC use as four alternative time-dependent variables (current use, current dose, cumulative dose and cumulative duration), adjusting for demographics, comorbidities, cardiovascular drug use, propensity score and RA characteristics. Sensitivity analyses explored potential effects of unmeasured confounding. RESULTS Within 50 238 person-years in 8384 RA cases, we identified 298 incident MI events. Multivariable models showed that current GC use was associated with 68% increased risk of MI [Hazard ratio (HR) = 1.68, 95% CI 1.14, 2.47]. Similarly, separate multivariable models showed that current daily dose (HR = 1.14, 95% CI 1.05, 1.24 per each 5 mg/day increase), cumulative duration of use (HR = 1.14, 95% CI 1.00, 1.29 per year of GC use) and total cumulative dose (HR = 1.06, 95% CI 1.02, 1.10 per gram accumulated in the past) were also associated with increased risk of MI. Furthermore, in the same multivariable model, current dose and cumulative use were independently associated with an increased risk of MI (10% per additional year on GCs and 13% per 5 mg/day increase). CONCLUSION GCs are associated with an increased risk of MI in RA. Our results suggest a dual effect of GCs on MI risk, an immediate effect mediated through current dosage and a long-term effect of cumulative exposure.

Independent impact of gout on the risk of acute myocardial infarction among elderly women: a population-based study

Background Men with gout have been found to have an increased risk of acute myocardial infarction (AMI), but no corresponding data are available among women. Objective To evaluate the potential independent association between gout and the risk of AMI among elderly women, aged ≥65 years. Methods A population-based cohort study was conducted using the British Columbia Linked Health Database and compared incidence rates of AMI between 9642 gout patients and 48 210 controls, with no history of ischaemic heart disease. Cox proportional hazards models stratified by gender were used to estimate the relative risk (RR) for AMI, adjusting for age, comorbidities and prescription drug use. Results Over a 7-year median follow-up, 3268 incident AMI cases, were identified, 996 among women. Compared with women without gout, the multivariate RRs among women with gout were 1.39 (95% CI 1.20 to 1.61) for all AMI and 1.41 (95% CI 1.19 to 1.67) for non-fatal AMI. These RRs were significantly larger than those among men (multivariate RRs for all AMI and non-fatal AMI, 1.11 and 1.11; p values for interaction, 0.003 and 0.005, respectively). Conclusion These population-based data suggest that women with gout have an increased risk for AMI and the magnitude of excess risk is higher than in men.

Gout and the risk of parkinson's disease: A cohort study

OBJECTIVE Several studies have suggested that higher serum uric acid levels lead to a lower risk of Parkinsons disease (PD) because uric acid exerts antioxidant effects on neurons. Our objective was to examine the relationship between gout and the risk of PD in persons age > or = 65 years. METHODS We conducted a population-based cohort study using the British Columbia Linked Health Database and PharmaCare data (i.e., prescription drug data for those age > or = 65 years). We compared incidence rates of PD between 11,258 gout patients and 56,199 controls matched on age, sex, date of gout diagnosis, and length of medical record. Cox proportional hazards models were used to estimate the relative risk (RR) of PD, adjusting for age, sex, prior comorbid conditions, and use of diuretics and nonsteroidal antiinflammatory drugs. RESULTS Over an 8-year median followup, we identified 1,182 new cases of PD. Compared with individuals without gout, the multivariate RR of PD among those with gout was 0.70 (95% confidence interval [95% CI] 0.59-0.83). In subgroup analyses, the inverse association was similarly present in both sexes and was evident among those who did not use diuretics (RR 0.66, 95% CI 0.54-0.81), but not among diuretic users (RR 0.80, 95% CI 0.58-1.10, P for interaction 0.35). CONCLUSION Our population-based data provide evidence for a protective effect of gout on the risk of PD and support the purported protective role of uric acid.

Validation of population-based disease simulation models: a review of concepts and methods

BackgroundComputer simulation models are used increasingly to support public health research and policy, but questions about their quality persist. The purpose of this article is to review the principles and methods for validation of population-based disease simulation models.MethodsWe developed a comprehensive framework for validating population-based chronic disease simulation models and used this framework in a review of published model validation guidelines. Based on the review, we formulated a set of recommendations for gathering evidence of model credibility.ResultsEvidence of model credibility derives from examining: 1) the process of model development, 2) the performance of a model, and 3) the quality of decisions based on the model. Many important issues in model validation are insufficiently addressed by current guidelines. These issues include a detailed evaluation of different data sources, graphical representation of models, computer programming, model calibration, between-model comparisons, sensitivity analysis, and predictive validity. The role of external data in model validation depends on the purpose of the model (e.g., decision analysis versus prediction). More research is needed on the methods of comparing the quality of decisions based on different models.ConclusionAs the role of simulation modeling in population health is increasing and models are becoming more complex, there is a need for further improvements in model validation methodology and common standards for evaluating model credibility.

Risk of Cardiovascular Disease in Patients With Osteoarthritis: A Prospective Longitudinal Study

To determine the risk of cardiovascular disease (CVD) among osteoarthritis (OA) patients using population‐based administrative data from British Columbia, Canada.

The relationship between osteoarthritis and cardiovascular disease in a population health survey: a cross-sectional study

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.

Effect of sociodemographic factors on surgical consultations and hip or knee replacements among patients with osteoarthritis in British Columbia, Canada.

Objective. To quantify the effect of demographic variables and socioeconomic status (SES) on surgical consultation and total joint arthroplasty (TJA) rates among patients with osteoarthritis (OA), using population-based administrative data. Methods. A cohort study was conducted in British Columbia using population data from 1991 to 2004. From April 1996 to March 1998, we documented 34,420 new patients with OA and these patients were followed to March 2004 for their first surgical consultation and TJA. Effects of age, sex, and SES were evaluated by Cox proportional hazards models after adjusting for comorbidities and pain medication used. Results. During a mean 5.5-year followup period, 7475 patients with OA had their first surgical consultations and 2814 patients received TJA within a 6-year mean followup period. Crude hazards ratio (HR) for men compared to women was 1.25 (95% CI 1.20–1.31) for surgical consultation and was 1.14 (95% CI 1.06–1.23) for TJA. The interaction between sex and SES was significant. Stratified analysis showed among men an HR of 1.42 (95% CI 1.27–1.58) and 1.52 (95% CI 1.26–1.83) for surgical consultations and TJA, respectively, for the highest SES compared with the lowest SES quintiles. Similarly significant results were observed among women. Conclusion. Differential access to the healthcare system exists among patients with OA. Women with OA were less likely than men to see an orthopedic surgeon as well as to obtain TJA. Patients with higher SES consulted orthopedic surgeons more frequently and received more TJA than those with the lowest SES.

Development of a population-based microsimulation model of osteoarthritis in Canada

OBJECTIVES The purpose of the study was to develop a population-based simulation model of osteoarthritis (OA) in Canada that can be used to quantify the future health and economic burden of OA under a range of scenarios for changes in the OA risk factors and treatments. In this article we describe the overall structure of the model, sources of data, derivation of key input parameters for the epidemiological component of the model, and preliminary validation studies. DESIGN We used the Population Health Model (POHEM) platform to develop a stochastic continuous-time microsimulation model of physician-diagnosed OA. Incidence rates were calibrated to agree with administrative data for the province of British Columbia, Canada. The effect of obesity on OA incidence and the impact of OA on health-related quality of life (HRQL) were modeled using Canadian national surveys. RESULTS Incidence rates of OA in the model increase approximately linearly with age in both sexes between the ages of 50 and 80 and plateau in the very old. In those aged 50+, the rates are substantially higher in women. At baseline, the prevalence of OA is 11.5%, 13.6% in women and 9.3% in men. The OA hazard ratios for obesity are 2.0 in women and 1.7 in men. The effect of OA diagnosis on HRQL, as measured by the Health Utilities Index Mark 3 (HUI3), is to reduce it by 0.10 in women and 0.14 in men. CONCLUSIONS We describe the development of the first population-based microsimulation model of OA. Strengths of this model include the use of large population databases to derive the key parameters and the application of modern microsimulation technology. Limitations of the model reflect the limitations of administrative and survey data and gaps in the epidemiological and HRQL literature.

Trends in physician-diagnosed osteoarthritis incidence in an administrative database in British Columbia, Canada, 1996-1997 through 2003-2004.

OBJECTIVE Prevalence of osteoarthritis (OA) is expected to increase due to population aging. However, there is little information on the trends in the incidence of OA over time. The purpose of this study was to describe changes in physician-diagnosed OA incidence rates between 1996-1997 and 2003-2004 in British Columbia (BC), Canada. METHODS We used data on all visits to health professionals and hospital admissions covered by the Medical Services Plan of BC (population approximately 4 million) for the fiscal years 1991-1992 through 2003-2004. Rates were standardized to the BC population in 2000. We used 2 definitions of OA: 1) at least 1 visit or hospitalization with a diagnostic code for OA, and 2) at least 2 visits or 1 hospitalization with a code for OA. Incidence rates were calculated with a 5-year run-in period to exclude prevalent cases. RESULTS Between 1996-1997 and 2003-2004, crude incidence rates of OA based on definition 1 increased from 10.5 to 12.2 per 1,000 in men and from 13.9 to 17.4 per 1,000 in women. The age-standardized rates did not change in men and increased from 14.7 to 16.7 per 1,000 in women. Incidence rates based on definition 2 were almost 50% lower, but the trends were similar. CONCLUSION We observed an increase in the incidence of OA in both men and women due to population aging and an additional increase in women beyond the effect of aging. These trends have important implications for public health and provision of health services to this very large group of patients.