Abstract
Income-based disparities has a profound impact on health outcomes by limiting access to preventive care, early diagnosis, and effective treatment with chronic conditions such as diabetes. Our aim was to investigate the impact of income-based disparities on diabetic foot amputation rates, focusing on disparities in outcomes among income levels. This retrospective cohort study used data from the Korean National Health Insurance Service database that tracked 2,580,585 diabetic patients between 2009 and 2012 (baseline) and followed them through 2019 using claims and mortality data to identify incident lower extremity amputation. Participants were categorized into income quartiles (Q1-Q4) with Q1 being the lowest-income group including Medical Aid beneficiaries. The primary outcome was the first occurrence of diabetes-related lower extremity amputation (LEA). LEA performance rates were inversely related to income, with Q1 + Medical Aid having the highest rate (0.64 per 1,00 person-years) and Q4 the lowest (0.45 per 1000 person-years). Adjusted models revealed a protective effect of higher income on LEA. The difference appeared to be more pronounced in individuals younger than 65 years, based on stratified analysis. Income-based disparities were observed in diabetic foot outcomes, with higher income groups showing improved limb preservation, especially among younger individuals. Given the observational design, these findings should be interpreted as associations rather than causal relationships. These findings suggest that targeted interventions may help reduce income-based disparities, alleviate the socioeconomic burden of diabetes, and improve quality of life in vulnerable populations.