Automated Oscillometric ABI Device and Underdiagnosis of Lower Extremity Atherosclerotic Disease

The automated oscillometric ankle-brachial index (ABI) recording device MEST ABPI MD® was found to overestimate low ABI and underestimate high ABI, making it unfavorable to use for detecting lower extremity atherosclerotic disease (LEAD). These findings were published in the Scandinavian Cardiovascular Journal.

This prospective observational cohort study was conducted at the Sahlgrenska University Hospital in Sweden. Patients (N=153) with and without known LEAD underwent routine ABI measurement using the automated oscillometric method with MEST ABPI MD® and manual measurement using Huntleigh Dopplex® D900 between 2018 and 2019. ABI measurements were compared for accuracy to predict LEAD.

The study population comprised 63% men aged mean 72±10 years, BMI was 26±4, 51% were former smokers, 72% had hypertension, 44% had hyperlipidemia, and 52% had LEAD.

During automated testing, 9% of tests returned an error code.

The automated and manual ABI evaluation found concordant pathological and normal results among 118 and 96 legs, respectively. Discordant results were found for 47 legs in which the automated measurement found pathological ABI and the manual assessment found normal ABI and in 39 legs the automated measurement found normal ABI and the manual assessment found pathological ABI.

These values indicated a sensitivity of 75%, specificity of 67%, positive predictive value (PPV) of 72%, and negative predictive value (NPV) of 71% for the automated device.

Stratified by gender, the automated device performed more poorly among men (sensitivity, 70%; specificity, 68%; PPV, 62%; NPV, 75%) than among women (sensitivity, 81%; specificity, 65%; PPV, 84%; NPV, 61%). Stratified by comorbidity, the automated device performed poorest among those with aortic dissection (sensitivity, 0%; specificity, 75%; PPV, 0%; NPV, 60%) and best for those with LEAD (sensitivity, 87%; specificity, 71%; PPV, 89%; NPV, 67%).

In general, automated and manual ABI measurements were moderately correlated (r, 0.552; P <.01). The linear regression analysis found proportional bias (P <.05), in which low ABI was overestimated and high ABI was underestimated.

This study may have been biased by the inability to blind the nurses who were performing the ABI measurements to assessment strategy.

“…the overall [MESI] ABPI MDVR® device performance—as compared to the manual ABI measurement method—was generally poor, limiting clinical usefulness,” the study authors wrote. “Our data therefore does not currently support the use of this automated ABI measurement device in clinical practice.”

Disclosure: None of the study authors has declared affiliations with biotech, pharmaceutical, and/or device companies.  

Reference

Zebari F, Amlani V, Langenskiöld M, Nordanstig J. Validation of an automated measurement method for determination of the ankle-brachial index. Scand Cardiovasc J. Published online May 2, 2022. doi:10.1080/14017431.2022.2069855