Economics of inpatient diabetic foot ulcer care in a multiethnic Asian population: a retrospective analysis of cost drivers and impact of high-cost users.

Introduction: Patients with diabetic foot ulcers (DFUs) have disproportionately high healthcare expenditures, with inpatient treatment accounting for the majority of the cost burden. Patients with multiple comorbidities and complex treatment have notably higher costs. Our study aims to evaluate the cost of inpatient DFU care, focusing on key cost drivers and the economic impact of high-cost users (HCUs). Methods: Patients admitted with a primary diagnosis of DFU from 1 January 2021 to 31 December 2023 were identified. Collected data included demographics, clinical variables, treatment details, outcomes and hospital financial records. The cohort was categorised into four cost groups: low (0th-25th percentile), intermediate (25th-75th percentile), high (75th-90th percentile) and extremely high (90th-100th percentile). Multivariable regression analyses were conducted to identify key cost drivers. Results: A total of 1677 patients were included, with a mean age of 65.7±12.4 years. The mean length of inpatient stay was 13.2±16.6 days. The median hospital cost per admission was US$11 790.02 (IQR: US$5456.54-US$25 948.55). The major amputation rate was 9.3%, and in-hospital mortality was 2.27%. Patients in the top 10% cost percentile-classified as HCUs (n=168)-accounted for approximately 40% of total DFU-related inpatient costs. This subgroup demonstrated a significantly higher comorbidity burden (peripheral vascular disease, osteomyelitis, end-stage renal failure and ischaemic heart disease) and underwent more surgical and revascularisation procedures, contributing to the key cost drivers. Despite this, they experienced poorer outcomes, with a major amputation rate of 42.86% and in-hospital mortality rate of 11.9%. Conclusions: DFU patients with multiple associated comorbidities result in complex and costly inpatient management. The simultaneous presence of multiple cost-driving factors gives rise to a HCU cohort that disproportionately contributes to healthcare expenditure while experiencing inferior clinical outcomes. Therefore, alongside clinical care optimisation, cost containment strategies should be integral to the multidisciplinary care model-particularly for patients at risk of becoming HCUs-to ensure the long-term sustainability of inpatient DFU management.