Abstract 288: Consistency of Hemoglobin A1C Testing and Amputation Risk

Abstract

Importance: While amputation rates have declined for patients with diabetes in the last decade, it remains unknown if preventive measures such as hemoglobin A1C testing have been associated with these improvements. Objective: To determine associations between hemoglobin A1c testing and amputation risk. Design, Setting, and Participants: We identified 11,942,840 Medicare patients with diabetes over the age of 65 between 2002-2012, and followed them for a mean of 6.6 years. We recorded the occurrence of lower-limb amputation and hemoglobin A1C testing. We examined associations between amputation risk and hemoglobin A1C testing. We measured both the presence of any testing, as well as testing consistency, using three categories: poor consistency (hemoglobin A1C testing in 0-50% of years), medium consistency (testing in 50-90% of years)), and high consistency (testing in >90% of the years in the cohort). Main Outcome Measure: Major (above or below-knee) amputation rate. Between 2002 and 2012, the incidence of major amputation in Medicare patients with diabetes declined by 54% during the study period, from 1.15 per 1,000 in 2002 to 0.53 per 1,000 in 2012 ( rate ratio = 0.53, 95% CI =0.51-0.54). Hemoglobin A1C testing increased from 78% of patients in 2002 to 83% of patients in 2012, and black and Hispanic patients were least likely to receive high consistency. In multivariable analysis adjusting for patient characteristics, including race, any use of hemoglobin A1C testing was associated with a 15% decline in amputation risk (HR 0.85, 95% CI 0.83-0.87, p<0.0001). However, high consistency hemoglobin A1C testing was associated with a 39% decline in amputation (HR 0.61, 95% CI 0.59-0.62, p<0.0001). Conclusions: Amputation rates have declined similarly across black, Hispanic, and white patients in recent years. Longitudinal quality measures emphasizing consistency in hemoglobin A1C testing may be an effective pathway towards limiting amputation in all races.