Objectives Patients with rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE) have an increased risk of developing coronary atherosclerosis. However, the impact of RA and SLE on the outcomes in patients undergoing percutaneous coronary intervention (PCI) remains largely underdetermined.

Methods Using the National Health Insurance Research Database of Taiwan, we identified 171 547 adult patients who underwent first-time PCI between 2000 and 2010. Among these patients, 525 had established RA, and 211 had SLE. The ORs of inhospital mortality and HRs of overall mortality and adverse cardiac outcomes after PCI (ie, ischaemic events, repeat revascularisation and major adverse cardiac events (MACE)) in relation to RA and SLE were estimated.

Results After adjustment for potential confounders, including patient characteristics and procedural variables, RA (OR=1.73, 95% CI 1.11 to 2.68) and SLE (OR=3.81, 95% CI 2.02 to 7.16) were independent predictors of inhospital mortality. In addition, RA was independently associated with overall mortality (HR=1.55, 95% CI 1.35 to 1.79), ischaemic events (HR=1.18, 95% CI 1.01 to 1.39) and MACE (HR=1.20, 95% CI 1.07 to 1.34) during long-term follow-up, whereas SLE was independently associated with overall mortality (HR=2.20, 95% CI 1.74 to 2.78), repeat revascularisation (HR=1.27, 95% CI 1.02 to 1.58) and MACE (HR=1.47, 95% CI 1.24 to 1.75). Compared with patients without autoimmune diseases, patients with more recent SLE-related hospitalisations prior to PCI were at higher risk of inhospital mortality (p for trend <0.0001).

Conclusions This study recognises the inherent risks associated with RA and SLE in patients undergoing PCI and highlights the necessity to improve the caring and secondary prevention strategies for these high-risk patients.