OBJECTIVES: Chronic lung allograft dysfunction (CLAD)-bronchiolitis obliterans syndrome (BOS) is a progressive, irreversible pulmonary disease where the immune system attacks airways in transplanted lungs leading to graft failure and death. CLAD-BOS severity is measured using CLAD stages 0-4 based on decreased forced expiratory volume in one second (FEV-1). Previous claims analyses were limited by the inability to identify CLAD stages due to the absence of an ICD-10 code and linkage to clinical measures. This analysis estimated costs by CLAD stage using claims data arising from a presumptive BOS diagnosis.

METHODS: A retrospective analysis of commercial claims was conducted using the PharMetrics^® Plus database. Patients <65 years old who underwent LTx between 1/1/2016 and 9/30/2018 and had ≥12 months of follow-up were included. Severe lung disease diagnosis codes were used as a proxy to identify LTx patients with BOS. Mean monthly healthcare costs were calculated from BOS diagnosis to end of follow-up for each patient and ranked from smallest to largest. A cross-sectional distribution of BOS stages was applied to mean monthly costs to segment patients by CLAD stage, with lowest monthly costs assigned CLAD-0 and highest CLAD-4. Mean monthly costs within each percentile range were calculated.

RESULTS: A total of 134 patients were included (mean age, 50.9 years; 64.9% male). Monthly cost ranges for each CLAD stage post-LTx were: CLAD-0 (N=69; range, $293-$7,148; mean, $4,037), CLAD-1 (N=31; range, $7,149-$17,545; mean, $10,678), CLAD-2 (N=20; range, $17,546-$36,173; mean, $26,629), CLAD-3 (N=7; range, $36,174-$55,216; mean, $50,751), CLAD-4 (N=7; range, $55,217-$267,249; mean, $118,431). Overall, hospitalizations comprised 78% of inpatient costs and ranged from 34% in CLAD-1 to 91% in CLAD-4.

CONCLUSIONS: Monthly costs for patients with BOS were substantial and further research in understanding costs by CLAD stage is warranted. Interventions aimed at treating CLAD-BOS may help decrease costs and provide benefit to patients.