The impact of hemoglobin A1c on outcomes after lower extremity bypass

Abstract

Objective: Diabetes has been shown to be associated with increased risk of postoperative complications after lower extremity bypass (LEB), although it is unclear whether medium-term glucose control affects outcomes. This study aimed to assess the association of perioperative hemoglobin A_1c (HbA_1c) level on perioperative outcomes after LEB.

Methods: We examined consecutive infrainguinal LEBs for chronic limb-threatening ischemia (CLTI) using the Vascular Quality Initiative database (2007-2018). Perioperative HbA_1c levels were stratified into <5.7%, 5.7% to 6.5%, and >6.5%. Propensity score matching on demographics, medical history, and procedural characteristics was used to select comparable patients across HbA_1c groups. The primary outcome was postoperative wound infection. Multivariable analyses were performed for matched and unmatched groups using Cox proportional hazards models for survival outcomes and logistic regression for binary outcomes with association expressed by adjusted hazard ratio (aHR) or adjusted odds ratio (aOR) and corresponding 95% confidence intervals (CIs).

Results: The CLTI cohort included 8171 infrainguinal LEBs: 631 (7.7%) had HbA_1c <5.7%; 1691 (20.6%), 5.7% to 6.5%; and 5849 (71.6%), >6.5%. There was no difference in rates of wound infection in the CLTI cohort (HbA_1c ≤5.7%, 3.8%; HbA_1c 5.7%-6.5%, 3.7%; HbA_1c >6.5%, 3.2%; P = .53) or matched cohort (4.3%, 4.5%, 3.4%; P = .62). There were no differences in perioperative mortality in the CLTI cohort (2.5%, 1.7%, 1.5%; P = .16) or the matched cohort (2.7%, 2.3%, 2.2%; P = .84). In multivariable analysis, there was no significant association between HbA_1c and wound infection in the CLTI cohort (HbA_1c 5.7%-6.5% vs <5.7%: aOR, 0.91 [95% CI, 0.56-1.50; P = .72]; HbA_1c >6.5% vs <5.7%: aOR, 0.81 [95% CI, 0.52-1.26; P = .35]). There was, however, a significant association between decreased HbA_1c and mortality (HbA_1c 5.7%-6.5% vs <5.7%: aHR, 0.77 [95% CI, 0.61-0.97; P = .03]; HbA_1c >6.5% vs <5.7%: aHR, 0.75 [95% CI, 0.61-0.93; P = .01]).

Conclusions: Our study suggests no significant association of increased HbA_1c level and perioperative complications. Additional investigation is required to further evaluate the impact of short-term glycemic control and long-term outcomes of patients undergoing LEB.

Keywords: Chronic limb threatening ischemia; Diabetes; Hemoglobin A1c; Lower extremity bypass.