Objectives: To investigate predictors of 10-year risk of revision and 1-year risk of prosthetic joint infection (PJI) and death following total hip/total knee arthroplasty (THA/TKA) in (1) patients with rheumatoid arthritis (RA) compared with patients with osteoarthritis (OA); and (2) patients with RA treated with biological diseasemodifying antirheumatic drugs (bDMARD) within 90 days preceding surgery compared with non-treated. Methods: Register-based cohort study using the Danish National Patient Register, the DANBIO rheumatology register (RA-specific confounders and treatment episodes) and the Danish Hip and Knee Arthroplasty Registers. Survival analyses were used to calculate confounder-adjusted sub-HRs (SHR) and HRs. Results: In total, 3913 patients with RA with THA/ TKA were compared with 120 499 patients with OA. Patients with RA had decreased risk of revision (SHR 0.71 (0.57-0.89)), but increased risk of PJI (SHR=1.46 (1.13-1.88)) and death (HR=1.25 (1.01-1.55)). In DANBIO, 345 of 1946 patients with RA with THA/ TKA had received bDMARD treatment within 90 days preceding surgery. bDMARD-treated patients did not have a statistically significant increased risk of revision (SHR=1.49 (0.65-3.40)), PJI (SHR=1.61 (0.70-3.69)) nor death (HR=0.75 (0.24-2.33)) compared with nontreated. Glucocorticoid exposure (HR=2.87 (1.12-7.34)) and increasing DAS28 (HR=1.49 (1.01-2.20)) were risk factors for mortality. Conclusion: Patients with RA had a decreased 10- year risk of revision while the risk of death and PJI was increased compared with patients with OA following THA/TKA. bDMARD exposure was not associated with statistically significant increased risk of neither PJI nor death in this study. Glucocorticoid exposure and increased disease activity were associated with an increased risk of death.