Multiple myeloma and infections: a population-based study on 9253 multiple myeloma patients

Infections are a major cause of morbidity and mortality in patients with multiple myeloma. To estimate the risk of bacterial and viral infections in multiple myeloma patients, we used population-based data from Sweden to identify all multiple myeloma patients (n=9253) diagnosed from 1988 to 2004 with follow up to 2007 and 34,931 matched controls. Cox proportional hazard models were used to estimate the risk of infections. Overall, multiple myeloma patients had a 7-fold (hazard ratio =7.1; 95% confidence interval = 6.8–7.4) risk of developing any infection compared to matched controls. The increased risk of developing a bacterial infection was 7-fold (7.1; 6.8–7.4), and for viral infections 10-fold (10.0; 8.9–11.4). Multiple myeloma patients diagnosed in the more recent calendar periods had significantly higher risk of infections compared to controls (P