BACKGROUND
BCMA-directed bispecific antibodies are increasingly used for relapsed/refractory multiple myeloma (MM), but real-world inpatient outcomes during early adoption remain limited.

METHODS
Adult MM hospitalizations from the 2022–2023 National Inpatient Sample were analyzed. BCMA-directed bispecific therapy was identified using ICD-10-PCS codes. Outcomes included mortality, length of stay (LOS), sepsis, acute respiratory failure (ARF), mechanical ventilation, and dialysis. Multivariable regression adjusted for age, sex, elective admission status, and year.

RESULTS
Among 50,013 MM hospitalizations, 1,715 (3.4%) involved BCMA-directed bispecific therapy. Utilization increased from 3.3% in 2022 to 3.6% in 2023.

Compared with non-bispecific admissions, bispecific-associated hospitalizations had:

• Higher mortality: 7.1% vs 5.0%
• Longer LOS: 9.6 vs 6.0 days
• More sepsis: 19.9% vs 15.0%
• More ARF: 39.2% vs 19.7%
• More mechanical ventilation: 4.7% vs 3.6%
• Less dialysis: 5.7% vs 8.3%

Bispecific therapy was independently associated with increased in-hospital mortality (aOR 1.45, P<0.001). Mortality was lower in 2023 than 2022 (aOR 0.83, P<0.001). The mortality gap was greatest in patients ≥75 years: 9.8% vs 6.1%.

CONCLUSION
BCMA-directed bispecific therapy was associated with greater inpatient resource use and higher infectious and respiratory complications. Improving mortality over time may reflect better toxicity recognition and management. Older adults appear particularly vulnerable.

TAKE-HOME MESSAGE
Close toxicity monitoring and risk-stratified inpatient care are essential as BCMA-directed bispecific therapy expands in real-world MM practice.