Survival in rheumatoid arthritis: a population-based analysis of trends over 40 years

Abstract

Objective: To evaluate trends in and risk factors for mortality among patients with rheumatoid arthritis (RA) over a 40-year period.

Methods: A population-based inception cohort was assembled from among all Rochester, Minnesota residents ages > or =18 years who were first diagnosed with RA (fulfilling the 1987 American College of Rheumatology criteria for RA) between January 1, 1955 and December 31, 1994. Patients were followed up longitudinally through their entire medical records (including all inpatient and outpatient care by any provider) until death or migration from the county. Survival was described using the Kaplan-Meier method. Observed and expected survival were compared using the log-rank test, and standardized mortality ratios (SMRs) with expected survival were based on the sex and age of the study population and death rates from the Minnesota life tables. Cox proportional hazards models were used to estimate the influence of extraarticular manifestations and comorbidities, controlling for age, sex, body mass index (BMI), smoking, and rheumatoid factor positivity.

Results: Survival in this RA cohort was significantly lower than that expected in the population (P < 0.001) over the entire time period. Patients with RA were at significantly higher risk of death, with an SMR of 1.27 (95% confidence interval 1.13-1.41). Excess mortality among women was more pronounced than among men, with SMRs of 1.41 and 1.08, respectively. Presence of > or =1 extraarticular manifestation was the strongest predictor of mortality after adjusting for age, sex, BMI, smoking, and rheumatoid factor positivity.

Conclusion: Survival in RA patients is significantly lower than expected. The strongest predictors of survival appear to be those related to RA disease complications, specifically, extraarticular manifestations of the disease and comorbidities. More attention should be paid to mortality as an outcome measure in RA.