Ankle-Brachial Index determination and peripheral arterial disease diagnosis by an oscillometric blood pressure device in primary care: validation and diagnostic accuracy study

Abstract

ObjectivesTo determine the level of agreement between a ‘conventional’ Ankle-Brachial Index (ABI) measurement (using Doppler and mercury sphygmomanometer taken by a research nurse) and a ‘pragmatic’ ABI measure (using an oscillometric device taken by a practice nurse) in primary care. To ascertain the utility of a pragmatic ABI measure for the diagnosis of peripheral arterial disease (PAD) in primary care.DesignCross-sectional validation and diagnostic accuracy study. Descriptive analyses were used to investigate the agreement between the two procedures using the Bland and Altman method to determine whether the correlation between ABI readings varied systematically. Diagnostic accuracy was assessed via sensitivity, specificity, accuracy, likelihood ratios, positive and negative predictive values, with ABI readings dichotomised and Receiver Operating Curve analysis using both univariable and multivariable logistic regression.SettingPrimary care in metropolitan and rural Victoria, Australia between October 2009 and November 2010.Participants250 persons with cardiovascular disease (CVD) or at high risk (three or more risk factors) of CVD.ResultsDespite a strong association between the two method's measurements of ABI there was poor agreement with 95% of readings within ±0.4 of the 0.9 ABI cut point. The multivariable C statistic of diagnosis of PAD was 0.89. Other diagnostic measures were sensitivity 62%, specificity 92%, positive predictive value 67%, negative predictive value 90%, accuracy 85%, positive likelihood ratio 7.3 and the negative likelihood ratio 0.42.ConclusionsOscillometric ABI measures by primary care nurses on a population with a 22% prevalence of PAD lacked sufficient agreement with conventional measures to be recommended for routine diagnosis of PAD. This pragmatic method may however be used as a screening tool high-risk and overt CVD patients in primary care as it can reliably exclude the condition.

Validity and reliability of the ankle-brachial index by oscillometric blood pressure and automated ankle-brachial index

“…[14] The oscillometric measurement of ABI had a good correlation with Doppler ultrasound measurements, and there was little difference between the two different machines tested. [15161718] Our results are in contrast to a previous study in which the oscillometric method compared to the Doppler method showed that it was of low sensitivity (50%), specificity (100%), Kappa (0.65), and correlations in ABIs were 0.46 for the left leg and 0.61 for the right leg. [19] Some studies have shown that automatic oscillometric ABI devices (BOSO ABI) cannot be used interchangeably for standard Doppler ABI measurement in diagnosing PAD, but their high negative predictive value allows their use as a screening tool for PAD.…”

The accuracy of an oscillometric ankle-brachial index in the diagnosis of lower limb peripheral arterial disease: A systematic review and meta-analysis

“…Eight studies included populations from Primary care services (mostly patients without symptoms of PAD), eight studies included populations from intermediate cardiovascular risk services and five studies included populations from Vascular services (mostly patients with symptoms of PAD). Weighted prevalence of PAD was 6.0% for Primary care, 25.5% for intermediate cardiovascular risk and 35.0% for Vascular services.…”

“…After exclusions, 1538 subjects (11 studies) and 3695 legs (11 studies) were analysed. Reasons for such exclusions were: (i) limb calcification, 16,17,[29][30][31][32][33][34] (ii) oscillometric errors 14,31,33,[35][36][37][38][39] and (iii) not all participants had their limbs measured using both the oscillometric and the Doppler. 40 In two studies, 16,17 a double analysis ("per subjects" and "per legs") was performed.…”

Different methods of calculating ankle-brachial index in mid-elderly men and women: the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil)

“…The Heinz Nixdorf RECALL is also applying this method with the same 1.0 ABI cut-off (11). For the purpose of a primary care setting and use in a cardiovascular prevention program, the oscillometric method is simple, less time consuming, and cheap (22 –25). Moreover, the variability of this device was lower compared to Doppler when applied in multicenter studies (25).…”