Androgen Deprivation Therapy for Prostate Cancer and the Risk of Rheumatoid Arthritis: A Population-Based Cohort Study

Introduction Two recent observational studies have investigated the association between androgen deprivation therapy (ADT) and rheumatoid arthritis (RA), but generated discrepant findings and had important methodological limitations. Thus, the objective of this study was to determine whether the use of ADT is associated with an increased risk of RA in men with prostate cancer. Patients and Methods We conducted a population-based cohort study using the United Kingdom Clinical Practice Research Datalink. The cohort included all men, at least 40 years of age, newly diagnosed with prostate cancer between 1 January 1988 and 31 March 2014, with follow-up until 30 September 2014. Exposure to ADT was treated as a time-varying variable and lagged by 1 year to account for diagnostic delays and latency. Cox proportional hazards models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) of RA, comparing use of ADT with non-use. Secondary analyses were conducted to assess whether the association varied according to ADT type and cumulative duration of use. Finally, we conducted several sensitivity analyses to assess the robustness of our findings. Results The cohort included 32,302 men followed for a median of 3.3 years. During follow-up, 63 patients were newly diagnosed with RA, generating an incidence rate of 46.5/100,000 person-years. Compared with non-use, the use of ADT was not associated with an increased risk of RA (HR 0.84, 95% CI 0.49-1.45). In secondary analyses, the association did not vary according to ADT type or with cumulative duration of use (p trend = 0.53). The results remained consistent in sensitivity analyses. Conclusion In this population-based study, the use of ADT was not associated with an increased risk of RA in men with prostate cancer.