Improving Outcomes for Diabetic Patients Undergoing Revascularization for Critical Limb Ischemia: Does the Quality of Outpatient Diabetic Care Matter?

Abstract

Diabetic patients who undergo lower extremity surgical revascularization for critical limb ischemia (CLI) are at high risk for amputation or death, even when their inpatient procedures are successful. We hypothesized that postoperative outcomes might be improved in regions where diabetics with CLI receive more frequent high-quality outpatient care. A retrospective cohort study was performed among 172,134 patients with CLI (52% male, 15% black, mean age 76years) who underwent open and endovascular lower extremity revascularization procedures using Medicare claims (2004-2007), which included 84,653 (49%) beneficiaries who were diabetic. Regional utilization of annual serum cholesterol and hemoglobin A1c testing were used to assess the quality of outpatient diabetic care. We examined relationships between frequency of diabetic testing with amputation-free survival (AFS), major adverse limb events (MALE), and rates of readmission across all US hospital referral regions. There was significant regional variation in annual serum cholesterol and hemoglobin A1c testing across the United States (87% highest quartile vs. 59% lowest quartile, P<0.01). Compared with the lowest quartile of diabetic testing, diabetic patients undergoing lower extremity revascularization in regions with the highest quartile of diabetic testing had significantly improved AFS (hazards ratio [HR]: 0.94, 95% confidence interval [CI]: 0.90-0.97; P<0.01) and MALE (HR: 0.92, 95% CI: 0.89-0.96; P<0.01) persisting up to 2 years after lower extremity revascularization, even after adjusting for procedure type, gender, age, race, and comorbidities. Moreover, the risk of 30-day readmission was significantly reduced in regions with the highest versus lowest quartile of diabetic testing (odds ratio: 0.91, 95% CI: 0.85-0.97; P<0.01). Nondiabetic patients with CLI, in comparison, did not benefit to the same extent from undergoing revascularization in regions with high-quality outpatient diabetic care. Diabetic patients undergoing lower extremity revascularization in regions with higher utilization of diabetic care quality measures have significantly better long-term limb salvage and readmission outcomes. Our study underscores the importance of providing optimal outpatient care to diabetics following vascular surgery and outlines a potential strategy for quality improvement in these high-risk patients.