Trends in excess mortality among patients with rheumatoid arthritis in Ontario, Canada
Widdifield J, Bernatsky S, Paterson JM, Tomlinson G, Tu K, Kuriya B, Thorne JC, Pope JE, Hollands S, Bombardier C. Arthritis Care Res (Hoboken). 2015; 67(8):1047-53. Epub 2015 Jan 26.
Objective — To evaluate excess mortality over time comparing rheumatoid arthritis (RA) patients with the general population.
Methods — The researchers computed all-cause mortality rates among Ontario residents aged ≥ 15 years with versus without RA from 1996 to 2009. Age/sex-standardized mortality rates were expressed as the number of deaths per 1000 population. Excess mortality rates were calculated as the difference between death rates among RA patients and those in the general population. The researchers estimated standardized mortality ratios (SMRs) and mortality rate ratios (MRRs) to assess relative excess mortality over time.
Results — From 1996 to 2009, standardized mortality rates in RA ranged from 13.0 (95% CI 12.2,13.9) to 9.2 deaths per 1000 RA patients (95% CI 8.4,10.0); and for those without RA from 8.7 (95% CI 8.6,8.7) to 6.0 deaths (95%CI 5.9,6.0) per 1000 general population. Over the study period, the excess mortality rate among RA patients was approximately 3 excess deaths per 1000 population. Relative reductions in standardized mortality rates occurred over time for those with and without RA (-21.4% vs. -13.4% respectively). The SMRs for RA patients in 1996-1997, 2000-2001, 2004-2005, and 2008-2009 were 1.51 (95% CI 1.43, 1.59), 1.50 (95% CI 1.43,1.57), 1.43 (95%CI 1.37,1.50), and 1.41 (95%CI 1.35,1.47) respectively. The researchers did not find a significant change in the MRR by calendar time.
Conclusion — Mortality for RA patients has decreased over time but remains elevated compared to the general population with 40-50% more deaths among RA patients. The relative excess mortality over time (mortality gap) remains unchanged in the sample.
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Chronic diseases and conditions