Subsequent leukaemia in autoimmune disease patients.

Previous studies have shown that patients diagnosed with some autoimmune (AI) diseases are at an increased risk of leukaemia but limited data are available on survival. We systematically analysed the risks (standardized incidence ratio, SIR) and survival (hazard ratio, HR) in nine types of leukaemia among 402 462 patients hospitalized for any of 33 AI diseases and compared to persons not hospitalized for AI diseases. Risk for all leukaemia was increased after 13 AI diseases and survival was decreased after six AI diseases. SIRs were increased after all AI diseases for seven types of leukaemia, including SIR 1·69 (95% confidence interval (CI): 1·29-2·19) for acute lymphoblastic leukaemia (ALL), 1·85 (95% CI: 1·65-2·07) for acute myeloid leukaemia, 1·68 (95% CI: 1·37-2·04) for chronic myeloid leukaemia, 2·20 (95% CI: 1·69-2·81) for 'other myeloid leukaemia', 2·45 (95% 1·99-2·98) for 'other and unspecified leukaemia', 1·81 (95% CI: 1·11-2·81) for monocytic leukaemia, and 1·36 (95% CI: 1·08-1·69) for myelofibrosis. The HRs were increased for four types of leukaemia, most for myelofibrosis (1·74, 95% CI: 1·33-2·29) and ALL (1·42, 95% CI: 1·03-1·95). Some AI diseases, including rheumatoid arthritis, were associated with increased SIRs and HRs in many types of leukaemia. The present data showed increases in risk and decreases in survival for many types of leukaemia after various AI diseases. Leukaemia is a rare complication in AI disease but findings about this comorbidity at the time of leukaemia diagnosis may help to optimize the treatment and improve survival.