OBJECTIVES: Infections are major causes of morbidity and mortality in multiple myeloma (MM). Daratumumab improved patient outcomes but increased the risk of infectious complications, including pneumonia. The aim of this study was to identify the effect of daratumumab on pneumonia using real-world data.

METHODS: Using the National Health Insurance database in Korea, patients with a history from the first- to fourth-line therapy of MM from 2007 to 2021 were included. We set the date of fourth-line therapy as the index date. We divided patients into two groups by the history of daratumumab. The start date for the was identified based on the earliest of the following: date of the first claim for new MM drugs or the first claim date for any MM therapy with a gap greater than 180 days after. The occurrence of pneumonia was defined as the first diagnosis of pneumonia during . Two groups were matched using 1:1 propensity score on age, sex, the year of the first-line therapy, pneumonia risk factors, etc. To compare the occurrence of pneumonia between the pre- and post-index period, we conducted the difference-in-differences (DID) analysis using the Cox proportional hazards model.

RESULTS: After matching, 578 patients (N=289 in each group) were identified. Comparing the baseline characteristics using standardized differences, only the year of the first-line therapy differed. Comparing daratumumab group and non-daratumumab group, there was a non-significant hazard of pneumonia in pre-index period (hazard ratio (HR), 1.019; 95% confidence interval (CI), 0.818-1.271) and in post-index period (HR, 1.097; 95% CI, 0.869-1.389). After adjusting for the year of the first-line therapy, the hazards before and after index date were still statistically non-significant between the two groups (DID HR, 0.930; 95% CI, 0.673-1.282).

CONCLUSIONS: In this study, daratumumab had no significant hazard on pneumonia in MM.