Shifting burden of major lower-extremity amputations across hospital Medicaid burden and socioeconomic groups, 1993 to 2021.

Abstract

Recent reports have identified a concerning reversal of previously declining trends in major lower-extremity amputations, driven by a combination of cardiovascular, societal, and hospital system-level factors. Our objective was to determine major lower-extremity amputation risk by patient resources and hospital setting-the former represented by zip code-based income quartile, race, and ethnicity (surrogates for socioeconomic status) and the latter characterized by hospital Medicaid proportion. Using the National Inpatient Sample, we identified inpatient admissions with diagnoses codes for atherosclerosis, chronic limb-threatening ischemia, and chronic occlusions between 1993 and 2021. Procedure codes identified below-the-knee amputation (BKA) and above-the-knee amputation (AKA). We calculated sample-weighted, population standardized incidence rates per 100,000 people by hospital Medicaid proportions (defined as quantiles with increasing proportions), zip code-based income quartile, race, and ethnicity. Landmark multivariable logistic regressions-with inflection points at 2010 for BKA and 2012 for AKA-identified adjusted associations between amputation risk, hospital Medicaid proportion quantile, income quartile, race, and ethnicity. In a sample of 2,769,388 admissions, there were 197,018 BKA and 151,018 AKA. Almost 42% of amputations, both AKA and BKA, were reported in the lowest income quartile, whereas 79% of major amputations were performed in the highest Medicaid proportion facilities. Preinflection points for both AKA and BKA, we note a clear, linearly increasing association between increasing hospital Medicaid proportion, low income, Black race, and amputation risk. In more recent periods, elevated risk persisted but became more evenly distributed across hospitals with moderate-to-high Medicaid burden. Notably for income, there was a widening gap in protective effect-adversely affecting those at the lowest quartiles. As amputation incidence rises, associated hospital and patient characteristics have changed accordingly. Previously concentrated in extreme settings, amputation burden now spans more hospital systems and pronouncedly impacts lower-income groups. These findings strongly encourage re-evaluating the process of care for patients at risk for major amputations.