Patient Outcomes After Index Amputations For Critical Limb-threatening Ischemia
Andres Guerra, Michelle Guo, Riley Boyd, Marina Zakharevich, Andrew Hoel, Ashley Vavra, Jeanette Chung, Karen Ho
Northwestern University Feinberg School of Medicine, Chicago, IL
INTRODUCTION: Factors associated with unplanned higher level reamputation (UHRA) among patients with critical limb-threatening ischemia (CLTI) who undergo lower extremity amputation are poorly understood. This study aims to identify factors associated with UHRA, any reamputation, return to the operating room and 1-year mortality after lower extremity amputation for CLTI.
METHODS: This is a single-center retrospective review of patients who underwent index amputations for CLTI between 2014 and 2017. Patient- and limb-level data were collected from the electronic medical record. Outcomes were unplanned higher-level reamputation (UHRA), any reamputation, return to the operating room for either closure, revision, debridement, revascularization or unplanned higher amputation, and 1-year mortality after index amputation. We report unadjusted bivariate associations and adjusted odds ratios (AOR) from logistic regression models of the association between each preamputation risk factor and each outcome controlling for age, race, sex, and amputation type.
RESULTS: Overall, 182 patients underwent 203 amputations (median age 65 years [IQR 57,75]; 70.7% males). Amputations included 118 toe (58.1%), 20 transmetatarsal (TMA; 9.9%), 37 below-knee (BKA; 18.2%), and 29 (14.3%) amputations at or above the knee. Indications for amputation included gangrene (n=82, 40.4%), infection (n=88; 43.4%), ulceration (n=25; 12.3%), and rest pain (n=8; 3.9%). Median follow-up was 302 days [IQR 62, 1348]. Thirty-six (17.7%) limbs had an UHRA, most occurring after toe amputation (n=26; 22.0%) or TMA (n=6; 30.0%). Revascularization prior to or concomitant with amputation was associated with increased UHRA (25.3% versus 12.5%, p=0.03). Risk factors associated with increased odds of UHRA included non-ambulatory status (AOR 6.74, CI 1.74-26.18; p<0.01), toe pressure <30 mm Hg (AOR 4.90, CI 1.52-15.78; p<0.01), and a monophasic or absent ankle waveform (AOR 3.12, CI1.30-7.46; p=0.01). Of the 203 lower extremity procedures, 72 (35.5%) underwent some form of reamputation during follow-up and 74 (36.5%) resulted in return to the operating room after index amputation. Lower-extremity procedures involving partially closed or open index amputation were more susceptible to any reamputation (48.51% vs 22.55% closed, p<0.001) with a 2.49 times greater odds (95% CI 1.18-5.23) of returning to the operating room. All-cause 1-year mortality was 17.2% (n=32 patients). Risk factors for 1-year mortality included CAD (AOR 3.93, CI 1.56 - 9.87; p<0.01), CHF (AOR 4.90, CI 1.96 - 12.29; p=0.001), ESRD (AOR7.54, CI 3.10 - 18.34; p<0.001), and non-independent ambulatory status (AOR 4.31, CI 1.20 - 15.49; p=0.03). Males had lower odds of 1-year mortality compared to females (AOR 0.37, CI 0.15 - 0.89; p=0.03). UHRA overall was not associated with 1-year mortality.
CONCLUSIONS: Determining the appropriate level of amputation for patients with CLTI can be difficult. Rates of UHRA after toe amputations and TMA are high despite revascularization. Patients with CLTI requiring amputation, regardless of subsequent UHRA, are at high risk of 1-year mortality. Larger multi-center datasets and hierarchical modeling of surgeon, patient, and limb-level factors may reveal further insights.
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