UBC Theses and Dissertations
Secular trends in risk of incident cardiovascular events in rheumatoid arthritis relative to the general population Yazdani, Kiana
Background: Recent evidence suggests a significant decline in all-cause and cardiovascular mortality over time in rheumatoid arthritis (RA) relative to the general population. This improvement in mortality could be due to improvement in risk of cardiovascular events that are the leading cause of excess deaths in RA. Our objective was to evaluate secular trends in ten-year risk of incident a. Acute Myocardial Infarction (AMI), and b. Cerebrovascular Accidents (CVA), in incident RA cohorts, according to their year of RA incidence, relative to the general population. Methods: We conducted two retrospective studies of a population-based cohorts of incident RA with RA onset from 01.01.1997 to 31.12.2004, in British Columbia, with matched general population. RA and general population cohorts were divided according to the year of RA incidence, defined based on the first RA visit, using a 7-year wash-out period. Chapter 2 and 3 describe the risk of incident a. AMI, and b. CVA respectively, using Cox delayed entry models to avoid immortal bias. To determine non-linear effect of years of incidence, Cox regressions, with linear, quadratic and spline functions of years of incidence were compared, and the model with the lowest AIC was selected to interpret the data. To assess whether the risk of AMI/CVA in RA differed from the general population, an interaction term between the indicator of RA vs general population and years of incidence was tested in the Cox models. Results: The decline in risk of AMI incidence did not differ significantly in RA vs. general population [interaction p=0.498]. The change in risk of incident CVA over time, differed significantly in RA vs. general population after 1999 [p=0.0393], but not before 1999 [p=0.0564]. Conclusion: There was a significant decline in10-year risk of AMI in RA, and this decline did not differ in RA vs. general population. There was a significant decline in 10-year risk of CVA in RA with onset from 1999 onwards, and this decline was to a greater extent in RA than it was in the general population.
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