Mortality estimates and excess mortality in rheumatoid arthritis

Objectives: To determine long-term (20 year) survival in RA patients enrolled in the Australian Rheumatology Association Database (ARAD).

Methods: ARAD patients with RA and data linkage consent who were diagnosed from 1995 onwards were included. Death data were obtained through linkage to the Australian National Death Index. Results were compared with age-, gender- and calendar year-matched Australian population mortality rates. Analysis included both the standardized mortality ratio (SMR) and relative survival models. Restricted mean survival time (RMST) at 20 years was calculated as a measure of life lost. Cause-specific SMRs (CS-SMRs) were estimated for International Classification of Diseases, Tenth Revision cause of death classifications.

Results: A total of 1895 RA patients were included; 74% were female, baseline median age 50 years (interquartile range 41-58), with 204 deaths. There was no increase in mortality over the first 10 years of follow up, but at 20 years the SMR was 1.49 (95% CI 1.30, 1.71) and the relative survival was 94% (95% CI 91, 97). The difference between observed (18.41 years) and expected (18.68 years) RMST was 4 months. Respiratory conditions were an important underlying cause of death in RA, primarily attributable to pneumonia [CS-SMR 5.2 (95% CI 2.3, 10.3)] and interstitial lung disease [CS-SMR 7.6 (95% CI 3.0, 14.7)], however, coronary heart disease [CS-SMR 0.82 (95% CI 0.42, 1.4)] and neoplasms [CS-SMR 1.2 (95% CI 0.89, 1.5)] were not.

Conclusion: Mortality risk in this RA cohort accrues over time and is moderately increased at 20 years of follow-up. Respiratory diseases may have supplanted cardiovascular diseases as a major contributor to this mortality gap.