Incidence, Recurrence, Timing, and Economic Impact of Infections After CAR T-Cell Therapy: A Real-World Analysis from MarketScan Database

• Over half of CAR T-cell recipients developed infections in real-world practice • Infection burden was substantial early and persisted beyond 90 days post CAR-T • Recurrent infections were frequent and varied by malignancy subtype and age • Infections led to substantial outpatient visits, hospitalizations, and LOS • Infection-related care resulted in meaningful patient out-of-pocket costs Chimeric antigen receptor (CAR) T-cell therapy has transformed treatment of hematologic malignancies but causes profound immune dysfunction and a high infections risk. Real-world data on infection incidence and economic burden remain limited. To characterize the incidence, recurrence, timing, and types of infections after CAR T-cell therapy and estimate infection-related clinic visits, hospitalizations, and patient out-of-pocket (OOP) costs. This retrospective cohort study used Merative MarketScan Commercial Claims Database (2017–2022). Adults (≥18 years) receiving CAR T-cell therapy for hematologic malignancies were included. Infections were identified via International Classification of Diseases, Tenth Revision (ICD-10) codes and classified by pathogen (bacterial, viral, fungal, unspecified) and organ system. Infections were examined across post-infusion intervals (90 days) and incidence rates were reported per 100 patient-years. Bivariate analyses compared baseline characteristics by infection status. Infection-related outpatient visits, hospitalizations, length of stay (LOS), and OOP costs were evaluated. Of 378 eligible patients, 213 (56%) developed ≥1 infection (289 events). Respiratory predominated the most common (34%). Overall incidence was 122 per 100 patient-years, peaking at 609 per 100 patient-years in days 30-90. Incidence differed significantly by hematologic malignancy subtype. Recurrent infections occurred in 157 patients (42%), totaling 1, 373 distinct events (median 4 per patient; IQR, 2-11) with respiratory tract infections also being the most common (30%). The median time from the first to recurrent infection was 24 days (IQR, 4-69). Recurrence varied significantly by malignancy subtype and patient age. A total of 127 patients (34%) had 447 infection-related outpatient visits, and 67 patients (18%) had 95 infection-related hospitalizations. Median LOS was 7 days (IQR, 3–14). Total OOP costs were approximately 7, 800 for outpatient visits and 35, 000 for hospitalizations. Infections are common, recurrent, and burdensome after CAR T-cell therapy, driving substantial healthcare utilization and OOP costs. Risk-stratified prophylaxis and management strategies are needed throughout the treatment continuum.