Impact of Invasive Mold Infection-Coded Diagnoses on Utilization, Costs, and Mortality After Lung Transplantation.

Abstract

Lung transplant recipients (LTRs) are highly susceptible to invasive mold infections (IMIs), In clinical practice, diagnostic codes for IMI serve as claims-based markers of suspected infection that often prompt antifungal therapy, but their real-world clinical and economic impact remains incompletely defined. Among lung transplant recipients, are IMI-coded diagnoses associated with increased healthcare utilization, costs, and mortality? We conducted a retrospective cohort study using the OptumLabs® Data Warehouse (2005-2023). Adult LTRs were identified by procedure codes and followed from transplant until disenrollment, death, or December 2023. IMIs were defined by ICD-9/10 codes. Risk factors were assessed using multivariable logistic regression. A 1:2 matched cohort (age, sex, transplant length of stay) evaluated healthcare utilization, costs, and mortality. Utilization and costs were calculated per patient-month (PPM) and stratified by payer. Mortality was assessed using Cox models. Among 1,120 eligible LTRs, 343 (30.6%; 95% CI, 27.9%-33.4%) had an IMI-coded diagnosis, most commonly aspergillosis (88%). Male sex (OR 1.52, 95% CI 1.16-1.99) and cystic fibrosis (OR 1.93, 95% CI 1.14-3.28) were independently associated with IMI coding, while higher comorbidity burden was associated with lower odds (OR 0.65, 95% CI 0.43-0.98). In the matched cohort (243 IMI, 486 non-IMI), IMI coding was associated with greater emergency department use (0.13 vs. 0.10 visits/PPM, p=0.018) and longer inpatient stay (3.28 vs. 2.23 days/PPM, p=0.031). Cost patterns diverged: commercially insured recipients with IMI-coded diagnoses had lower pharmacy costs ($3,416 vs. $4,504/PPM, p=0.006), while Medicare Advantage recipients incurred significantly higher inpatient, medical, and overall costs. IMI coding was associated with nearly two-fold higher mortality (HR 1.83, 95% CI 1.33-2.51, p<0.001). IMI-coded diagnoses are common after lung transplantation and are associated with greater acute care utilization, higher costs among Medicare Advantage recipients, and increased mortality. These findings underscore the clinical and economic burden of suspected mold infections in LTRs and highlight the need for integrated claims and clinical data to refine prevention strategies.