Economic Burden of Cachexia in Japanese Lung Cancer Patients: A Retrospective Claims Database Analysis

Cancer cachexia is associated with poor clinical outcomes in lung cancer patients; however, its economic impact in Japan remains largely uncharacterized. This study quantified the incremental healthcare costs associated with cachexia in Japanese lung cancer patients using nationwide claims data. We conducted a retrospective cohort study using the Japan Medical Data Center Claims Database. Deceased lung cancer patients were classified into cachexia (n = 447) and control (n = 10464) groups based on International Classification of Diseases, 10th Revision diagnosis codes. Between-group cost differences were assessed using generalized linear models with a gamma distribution, adjusting for survival time, demographics, histology, metastasis, and comorbidities. Within-patient cost changes were analyzed using fixed-effects regression, comparing 6-month periods before and after cachexia diagnosis. Cachexia was independently associated with 13.5% higher total medical costs (rate ratio: 1.14, 95% confidence interval [CI]: 1.06-1.21, p < 0.001). Within-patient analysis demonstrated a 57.9% cost increase in the month of diagnosis (from ¥371360 to ¥586405), with costs remaining 21.7% elevated post-diagnosis. Cost composition shifted from procedures (1.3 vs. 5.4%) toward home care (8.6 vs. 5.7%) in cachexia patients. Median survival following cachexia diagnosis was only 1.0 month, with 71% of patients dying within 3 months. Anamorelin use increased from 2.4 to 29.8% post-diagnosis, although 70.2% of patients did not receive this therapy. Cachexia diagnosis in lung cancer patients is associated with substantial cost increases in Japan. The extremely short survival after diagnosis and the shift toward supportive care highlight the need for earlier recognition and intervention. These findings provide essential data for the economic evaluation of cachexia therapies.