Chronic hepatitis B is associated with an increased risk of B‐cell non‐Hodgkin's lymphoma and multiple myeloma

SUMMARY Background Chronic hepatitis B has been linked to lymphoma with contradictory results. Aim To investigate the association between chronic hepatitis B and lymphoma by using a nationwide population‐based cohort. Methods Records of patients diagnosed with chronic hepatitis B (hepatitis B virus [HBV] cohort) or without (non‐HBV cohort) during 2004‐2007 were retrieved from the Taiwan National Health Insurance Research Database. Age, sex, comorbidities, and medical visits were matched using propensity scores between both cohorts, and they were followed up longitudinally until 2012 to determine any new lymphoma development. Results A total of 203 031 patients were included in each cohort with a mean follow‐up of 7‐9 years. The lymphoma incidence rate was significantly higher in the HBV cohort than in the non‐HBV cohort (29.4 vs 15.9 per 100 000 person‐years, P