Variability in 30-day major amputation rates following endovascular peripheral vascular intervention for critical limb ischemia

Introduction: Patients with critical limb ischemia (CLI) can undergo endovascular peripheral vascular intervention (PVI) to restore blood flow and decrease risk of amputation. As a potential indicator of quality for CLI care, we sought to describe 30-day major amputation rates following PVI. We also examined rate variability, and patient-level and site-level factors predicting amputations, using a national electronic health record (EHR) database. Methods: Using the Cerner Health Facts de-identified EHR database, patients with CLI diagnosis codes undergoing PVI were identified. The rate of amputation within 30 days of PVI was calculated. Risk ratios predicting amputation were derived using a mixed effects Poisson regression model adjusting for 16 patient and clinical factors. Median risk ratios (MRRs) were calculated to quantify site-level variability in amputations. Results: A total of 20,204 PVI procedures for CLI from 179 healthcare sites were identified. Mean age at procedure was 69.0 +/- 12.6 years, 58.0% were male, and 29.6% were persons of color. Amputation within 30 days of PVI occurred after 570 (2.8%) procedures. Malnutrition, previous amputation, diabetes, and being of Black race were predictors of amputation. Amputation rates across sites ranged from 0.0% to 10.0%. The unadjusted MRR was 1.40 (95% CI 1.35-1.46), which was attenuated after adjusting for patient-level factors (MRR 1.30, 95% CI 1.26-1.34) and site characteristics (MRR 1.11, 95% CI 1.09-1.13). Conclusions: Among PVI procedures for CLI treatment, 30-day amputation rates varied across institutions. Although patient-level factors explained some variability, site-level factors explained most variation in the rates of these outcomes.