Increased Risk of Infections and Mortality Following Fractures in Multiple Myeloma: A Nationwide Population-Based Retrospective Cohort Study.

BACKGROUND AND AIMS: To determine whether patients with MM face higher risks of hospitalized infections and long-term all-cause mortality after a first fracture than non-MM fracture patients at the population level. METHODS: We performed a nationwide retrospective cohort study using Taiwan National Health Insurance Research Database from 2001 to 2019. Adults with MM and non-MM adults with an index hospitalized fracture were identified and matched 1:10 by propensity scores. Cox proportional-hazards models and Kaplan-Meier analyses compared risks of lower respiratory tract, reproductive or urinary tract, intra-abdominal, and skin and soft-tissue infections requiring hospitalization, as well as all-cause mortality. RESULTS: During 2001-2019, the incidence and age-standardized incidence of MM in Taiwan were 6.0 and 5.4 per 100,000 people, respectively, and both increased over time. After propensity-score matching, 303 MM patients with a first hospitalized fracture were compared with 3,030 non-MM fracture patients. Compared with matched non-MM patients, MM patients had significantly higher risks of lower respiratory tract infections (adjusted hazard ratio [AHR] = 2.12, 95% confidence interval [CI]: 1.72-2.61; p < 0.001), reproductive or urinary tract infections (AHR = 1.40, 95% CI: 1.06-1.86; p = 0.019), and all-cause mortality (AHR = 1.98, 95% CI: 1.72-2.28; p < 0.001). The corresponding incidence rates per 1,000 person-years were also higher in MM than non-MM patients for lower respiratory tract infections (237.96 vs. 60.92), reproductive or urinary tract infections (107.35 vs. 41.26), skin and soft-tissue infections (28.77 vs. 15.30), and all-cause mortality (271.67 vs. 84.39). These associations were generally consistent across subgroups stratified by age, sex, and fracture type. CONCLUSION: MM was associated with substantially higher risks of serious infections and death after fracture. These findings support early multidisciplinary post-fracture care, including infection surveillance and prevention, in MM patients.