Myocardial infarction and mortality following joint surgery in patients with rheumatoid arthritis: a retrospective cohort study

BACKGROUND Rheumatoid arthritis (RA) is associated with an increased risk of myocardial infarction (MI) and post-MI fatality compared with the general population. In a previous study examining post-MI treatment in RA compared with controls we noted that a higher proportion of the RA patients had experienced MI following a surgical procedure. The aim of this study was to compare the risk of MI and mortality at 6 weeks and 12 months following joint surgery in patients with RA compared with the general population. METHODS Individuals who had undergone joint surgery in Victoria, Australia between 1 July 2000 and 30 June 2007 were identified from routinely collected hospital administrative data. Logistic regression analysis was performed to examine odds of 6 week and 12 month MI and mortality in RA versus non-RA patients with adjustment for age, sex, comorbidities, socioeconomic status, patient type and admission type. Subgroup analysis of total hip and knee arthroplasty episodes was undertaken. RESULTS A total of 308,589 episodes of joint surgery occurred among 240,571 individuals, with 3654 (1.2 %) occurring among patients with RA. At 6 weeks post joint surgery the adjusted odds ratio (OR) for MI was 1.50 (95 % CI 0.96-2.33), all-cause death was 1.85 (95 % CI 1.09-3.13) and cardiovascular death was 1.90 (95 % CI 1.07-3.37). At 12 months post joint surgery the adjusted OR of MI was 1.70 (95 % CI 1.27-2.28), all-cause death was 2.18 (95 % CI 1.66-2.86) and cardiovascular death was 2.30 (95 % CI 1.65-3.22). On analysis of joint surgeries other than hip or knee arthroplasty, people with RA were at greater risk of MI within 6 weeks (adjusted OR 2.32; 95 % CI 1.24-4.34) and 12 months (adjusted OR 2.20; 95 % CI 1.47-3.30) compared to those without RA, but no difference in odds of short term mortality were found. CONCLUSIONS Following an episode of joint surgery RA patients have a significantly increased risk of death at 6 weeks, and MI and death at 12 months, compared to the general population. The reasons for this remain to be elucidated but in the meantime RA patients should be considered at higher risk in the perioperative period.