Frailty Index associated with postoperative complications and mortality after lower extremity amputation in a national veteran cohort

Abstract

Objective: Surgical frailty and its assessment have become essential considerations in perioperative management for the modern aging surgical population. The risk analysis index is a validated frailty score that has been proven to predict short-term outcomes and long-term mortality in several surgical subspecialties and high-risk procedures. We examined the association of risk analysis index scores with postoperative outcomes in a retrospective nationwide database of patients who underwent lower extremity amputation in the Veterans Health Administration Health Care System.

Methods: The Veteran Affairs Surgical Quality Improvement Program data was queried across the Veteran Affairs Health Care System with institutional review board approval for lower extremity amputations. Records of above and below knee amputation, Current Procedural Terminology codes 27590, 27591, 27592, 27594, 27596 and 27880, 27881, 27882, 27884, and 27886, respectively, from 1999 to 2018 were obtained. Incomplete and traumatic entries were removed. Risk Analysis Index score was calculated from preoperative variables and patients were separated into five score cohorts (≤15, 16-25, 26-35, 36-45, ≥46). The χ² test and analysis of variance were used to compare the cohorts. Forward binary logistic regression modeling was used to determine covariate-adjusted odds ratios for outcomes in each cohort (SPSS software; version 25, IBM Corp).

Results: A total of 47,197 patients (98.9% male) with an average age of 66.4 ± 10.6 years underwent nontraumatic lower extremity amputation, including 27,098 below knee and 20,099 above knee amputations, during the study period. Frailty was associated with increased rates of deep vein thrombosis, sepsis, cardiac arrest, myocardial infarction, pneumonia, intubation for more than 48 hours, pulmonary embolism, reintubation, acute kidney injury, renal failure, increased length of stay, overall complications, and death. Increases in the frailty score were associated with up to three times the likelihood for the occurrence of a postoperative complication and up to 32 times likelihood to perish within 30 days than those with low frailty scores.

Conclusions: Risk analysis index assessment of frailty was found to be associated with several postoperative outcomes in a dose-dependent manner in patients undergoing lower extremity amputation in the Veterans Health Care System, with higher scores associated with higher rates of death and major cardiac (myocardial infarction, cardiac arrest), pulmonary (pneumonia, failure to wean vent, reintubation), and renal (renal insufficiency, renal failure) complications. We recommend the use of risk analysis index score as a frailty screening tool for patients undergoing lower extremity amputation to enable providers to adequately inform and counsel patients regarding potential significant risks.

Keywords: Amputation; Complications; Frailty; Lower extremity; Mortality; Risk analysis index; Vascular.