Excess Heart Disease Risk Associated with Arthritis in the Canadian General Population

This thesis, through three manuscripts, aims to clarify to what extent arthritis may be an independent risk factor for developing heart disease in the general population, underlying mechanisms of the relationship, and who may be most at-risk. Manuscript 1 is a systematic review and meta-analysis of population-based studies that estimated risk of incident myocardial infarction (MI) associated with five major types of arthritis. Results showed that MI-risk was consistently increased across arthritis and was partially explained by a higher prevalence of traditional heart disease risk factors in each type of arthritis. Knowledge gaps from the review were used to inform subsequent secondary analyses of the longitudinal Canadian National Population Health Survey (NPHS) with 16-years of follow up. Manuscript 2 used discrete time survival analysis with time-varying lagged predictors to estimate effects of arthritis on first heart disease event occurrence. Potential variations by age, sex and activity limitation were examined. Results showed that arthritis was independently associated with incident heart disease in all women, with more marked risk in women who also reported activity limitation, but only in men with activity limitation. Manuscript 3 used a novel approach to estimate potential mediating and moderating effects of activity limitation in the arthritis-heart disease relationship and possible differences by obesity and sex/gender in the same longitudinal health survey as manuscript 2. Results showed the proportion of heart disease risk explained by activity limitation varied between men and women, and between obese and non-obese women. Activity limitation explained nearly all of the heart disease risk associated with arthritis in men (90%), most of the heart disease risk in obese women (54%), and part of the heart disease risk in non-obese women (23%). Overall, the thesis results are important for increasing public and healthcare-provider awareness of excess heart disease risk generally associated with arthritis, highlighting sex/gender disparities, and identifying activity limitation as a modifiable intermediate target for prevention strategies to help reduce heart disease risk in people with arthritis.Ph.D