Increased risk of periodontitis in patients with rheumatoid arthritis: A nationwide register study in Norway

Abstract Aim To investigate the risk of periodontitis in rheumatoid arthritis (RA) patients in a nationwide register‐based study. Materials and Methods Patients and controls were defined using ICD‐10 codes registered in the Norwegian Patient Registry (NPR), from 2011 to 2017. The 324,232 included subjects had at least one registered diagnostic code for RA (33,040 patients) or diagnostic codes for non‐osteoporotic fractures or hip or knee replacement due to osteoarthritis (controls). The outcome was periodontitis, defined by codes for periodontal treatment from the Norwegian Control and Payment of Health Reimbursements Database (KUHR). Hazard ratios (HRs) were calculated for periodontitis in RA patients compared to controls. Generalized additive model in Cox regressions was estimated to visualize periodontitis occurrences as a function of number of RA visits. Results The risk of periodontitis increased with increasing number of RA visits. RA patients having 10 or more visits during the 7‐year period had a 50% increased risk of periodontitis compared to controls (HR = 1.48, 95% confidence interval [CI]: 1.39–1.59); also, in patients with assumed new RA, an even higher risk estimate was seen (HR = 1.82, 95% CI: 1.53–2.17). Conclusions In this register‐based study in which periodontal treatment was used as a surrogate marker for periodontitis, we found an increased risk of periodontitis in RA patients, particularly those with active disease and new RA.