Higher risk of hospitalized infection, cardiovascular disease, and fracture in patients with rheumatoid arthritis determined using the Japanese health insurance database

Objective: To evaluate the risk of hospitalized infection (HI), cardiovascular disease (CVD), stroke, and fracture in rheumatoid arthritis (RA) patients compared with non-RA patients using the Japanese health insurance database.

Method: Among individuals aged ≥18 years, RA cases were defined to have one RA diagnostic code and receiving ≥1 disease-modifying antirheumatic drug between 2005 and 2013 (n = 6,712). Age-, sex-, calendar year of the observation start-, and observation length-matched non-RA cases were selected at 1:5 (n = 33,560). Hazard ratios (HRs) were calculated using the time-dependent Cox regression analysis.

Results: Median age of the patients was 52.0 years. The incidence rates of HI, CVD, and fracture in the RA group were 2.42/100 person-years (PY), 4.94/1,000 PY, and 10.59/1,000 PY. The crude incidence rate ratios (95% CI) (RA vs. non-RA) for HI, CVD, and fracture were 2.47 (2.20–2.77), 1.89 (1.49–2.41), and 3.35 (2.80–4.02). The adjusted HR (95% CI) (RA vs. non-RA) was significantly elevated (HI, 1.74 [1.52–1.99], CVD, 1.38 [1.04–1.85], and fracture, 1.88 (1.54–2.31)].

Conclusion: The relatively young RA population had significantly higher risks of these complications than the non-RA, indicating importance of prevention of them even at young ages in clinical settings.