Impact of human immunodeficiency virus on in-hospital outcomes among patients hospitalized with multiple myeloma: A National Inpatient Sample study, 2016–2022.

7552 Background: Outcomes among hospitalized patients with multiple myeloma (MM) and concomitant human immunodeficiency virus (HIV) infection remain incompletely characterized at a national level. We evaluated the association of HIV infection with in-hospital outcomes among MM hospitalizations in the United States. Methods: We analyzed 161,303 MM hospitalizations and identified HIV infection using ICD-10 diagnosis codes (B20–B24, Z21). To improve comparability, we restricted analyses to hospitalizations with length of stay (LOS) < 30 days and complete covariate data, then performed 1:1 propensity score matching using demographics, hospital characteristics, Charlson comorbidity category, and key comorbidities. Primary outcome was in-hospital mortality. Secondary outcomes included LOS, total hospital charges, and inpatient complications. Results: Of 161,303 MM hospitalizations, 0.4% (n = 681) had HIV infection. After applying analytic restrictions, 458 HIV-positive hospitalizations were matched to 458 HIV-negative hospitalizations with good covariate balance; mean age was 60.0 years. HIV infection was not associated with higher in-hospital mortality (OR 0.68, 95% CI 0.37–1.21; p = 0.191). Median LOS was similar between groups (5 days in both); however, on log-transformed analysis HIV infection was associated with shorter LOS (LOS ratio 0.90; p = 0.033). HIV infection was associated with a nonsignificant trend toward lower total hospital charges (cost ratio 0.88, 95% CI 0.77–1.01; p = 0.061). HIV infection showed nonsignificant trends toward increased venous thromboembolism, including pulmonary embolism (OR 4.05; p = 0.078) and deep vein thrombosis (OR 1.88; p = 0.085). No significant differences were observed for mechanical ventilation or cerebrovascular accident. Conclusions: In matched analyses of MM hospitalizations, HIV infection was not associated with increased in-hospital mortality and was associated with shorter LOS despite similar median LOS. Total charges were not significantly different, though a trend toward lower charges was observed. Signals for increased venous thromboembolism warrant further study in larger cohorts.