Objective Excess mortality in rheumatoid arthritis (RA) is expected to have improved over time, due to improved treatment. Our objective was to evaluate secular 5-year mortality trends in RA relative to general population controls in incident RA cohorts diagnosed in 1996–2000 vs 2001–2006.
Methods We conducted a population-based cohort study, using administrative health data, of all incident RA cases in British Columbia who first met RA criteria between January 1996 and December 2006, with general population controls matched 1:1 on gender, birth and index years. Cohorts were divided into earlier (RA onset 1996–2000) and later (2001–2006) cohorts. Physician visits and vital statistics data were obtained until December 2010. Follow-up was censored at 5 years to ensure equal follow-up in both cohorts. Mortality rates, mortality rate ratios and HRs for mortality (RA vs controls) using proportional hazard models adjusting for age, were calculated. Differences in mortality in RA versus controls between earlier and later incident cohorts were tested via interaction between RA status (case/control) and cohort (earlier/later).
Results 24 914 RA cases and controls experienced 2747 and 2332 deaths, respectively. Mortality risk in RA versus controls differed across incident cohorts for all-cause, cardiovascular diseases (CVD) and cancer mortality (interactions p<0.01). A significant increase in mortality in RA versus controls was observed in earlier, but not later, cohorts (all-cause mortality adjusted HR (95% CI): 1.40 (1.30 to 1.51) and 0.97 (0.89 to 1.05), respectively).
Conclusions In our population-based incident RA cohort, mortality compared with the general population improved over time. Increased mortality in the first 5 years was observed in people with RA onset before, but not after, 2000.
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Handling editor Tore K Kvien
Contributors All authors contributed to the conception and study design. DL and AA-Z contributed to data acquisition, all authors contributed to data analysis or interpretation; all authors contributed to drafting or reviewing the manuscript and all approved the final draft of the manuscript.
Funding This study was funded by the Canadian Institute for Health Research (#32615), who played no role in the design or conduct of the study, other than providing peer-review of the study proposal.
Competing interests None declared.
Ethics approval University of British Columbia Ethics Board.
Provenance and peer review Not commissioned; externally peer reviewed.
Data sharing statement Results from sensitivity analyses not presented in full in the manuscript including in supplementary files are available on request to the corresponding author.
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