Medical cost of postoperative delirium after highly invasive cancer resection: a prospective cohort study

BACKGROUND: Postoperative delirium (POD) is a common and serious complication, especially among older adults. The economic burden of POD, particularly in patients undergoing highly invasive cancer resection who are at high risk of delirium, remains unclear. We aimed to clarify the economic burden of subsyndromal delirium (SSD) and severe delirium in this population. METHODS: We prospectively enrolled 281 adults undergoing highly invasive cancer resection and evaluated the impact of severe delirium and SSD diagnosed using the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, and the Delirium Rating Scale-Revised-98 severity scale. The primary outcome was diagnosis procedure combination (DPC) costs. Propensity score matching was performed to estimate the effect of delirium within a background-matched cohort, and generalized estimating equations with two-way cluster-robust standard errors were applied at both matched-set and patient levels. Sensitivity analyses were performed using direct medical costs (fee-for-service [FFS]). RESULTS: Fifty-five patients (19.6%) developed severe delirium. DPC costs showed no significant mean difference, whereas total FFS costs were significantly higher in severe delirium (mean difference: US$2364, 95%CI: US$122 ~ US$4606). Component analyses indicated higher costs for prescriptions, infusions, wound-related procedures, and laboratory tests. SSD had no significant economic impact. CONCLUSION: Severe postoperative delirium after highly invasive cancer resection was associated with increased FFS expenditures, particularly for prescriptions, infusions, wound care, and laboratory tests, whereas no significant differences were observed in DPC costs. Findings underscore the importance of preventing severe delirium.