Photoplethysmography: A Simplified Method for The Office Measurement of Ankle Brachial Index in Individuals with Diabetes

Abstract

To compare the use of photoplethysmography (PPG) and Doppler techniques to measure the ankle brachial index (ABI) for the evaluation of peripheral arterial disease (PAD) in individuals with diabetes. Consecutive patients with diabetes (n = 103) referred for PAD evaluation had ABI measured by PPG and Doppler techniques in our diabetes center. Medical records were reviewed, and the results of the Doppler and PPG testing were compared. Mean age was 60 years, 57% were female, and 79% had type 2 diabetes with an average duration of 17 years. PPG readings could not be obtained in 3 individuals. Of 200 limbs evaluated, 17 (8.5%) had noncompressible (NC) vessels by both techniques. In the remaining 183 limbs, the correlation coefficient comparing the two methods was 0.864. Mean ABI values were 1.11 ± 0.14 for Doppler and 1.12 ± 0.14 for PPG. The sensitivity of PPG compared to the Doppler technique for detection of an abnormal result was 88.2%, and the specificity was 99.4%. ABI results were classified as discordant if Doppler and PPG varied by more than 0.15, placing them in different diagnostic categories (abnormal low [≤0.9], borderline [0.91-0.99], normal [1.0-1.4], or abnormal high [>1.4 or NC vessels]). There were only 4 (2%) discordant results. We found excellent concordance between PPG and the gold standard Doppler technique for ABI measurement in individuals with diabetes. PPG requires less training and takes less time to perform, making it highly suitable for use in an office setting.