Variation in measurement of ankle-brachial pressure index in routine clinical practice

Purpose: The purpose of this study was to determine the Variation in ankle-brachial pressure index (ABPI) measurements in routine clinical practice. Methods: Analysis was done of preoperative and postoperative ABPIs in 130 limbs contralateral to those undergoing femoral bypass grafting in 123 patients over a 15-month period. Results: The mean initial ABPI was 0.72 (range 0.22 to 1.10). The range of observed differences between the preoperative and postoperative ABPIs was from -0.33 to +0.25. The mean (+SD) difference between the first and second ABPIs was 0.00 (+0.11). The 95% confidence limits of the difference were -0.21 to 0.21. There was no trend for the size or direction of the difference in ABPI to vary according to the mean ABPI, brachial blood pressure, or time between tests. Conclusions: ABPI is routinely used as an objective measure of peripheral vascular disease. The variation observed in this study is comparable with values obtained in reproducibility studies and is greater than that accepted in clinical practice. The difference between an ABPI measurement and the actual ABPI and the difference between repeat single measurements are not the same and should be distinguished. Vascular laboratories should determine the accuracy of ABPI measurement on a local basis to guarantee and maintain quality assurance.