Clinical validation of smartphone-based activity tracking in peripheral artery disease patients

• DOI: 10.1038/s41746-018-0073-x
• Publication Date: 2018-12-05T10:46:11Z
• Authors: Raheel Ata; Neil Gandhi; Hannah Rasmussen; Osama El-Gabalawy; Santiago Gutierrez; Alizeh Ahmad; Siddharth Suresh; Roshini Ravi; Kara Rothenberg; Oliver Aalami
• Keywords: Intermittent claudication; Activity monitor; Claudication

Abstract Peripheral artery disease (PAD) is a vascular that leads to reduced blood flow the limbs, often causing claudication symptoms impair patients’ ability walk. The distance walked during 6-min walk test (6MWT) correlates well with patient symptoms, so we developed VascTrac iPhone app as platform for monitoring PAD using digital 6MWT. In this study, evaluate accuracy of built-in and step-counting algorithms 6MWTs. One hundred fourteen (114) participants performed supervised 6MWT while simultaneously wearing an ActiGraph GT9X Activity Monitor. Steps distance-walked were manually measured used assess bias in CMPedometer algorithms. step algorithm underestimated steps −7.2% ± 13.8% (mean SD) had mean percent difference Actigraph (Actigraph-iPhone) 5.7% 20.5%. overestimated 43% 42% due overestimation stride length. Our correction factor improved estimation 8% 32%. Ankle-Brachial Index (ABI) correlated poorly ( R = 0.365) 0.413). Thus, patients, iPhone’s unable accurately measure distance, suggesting custom are necessary iPhones patients. Although steps, more research establish counting clinically meaningful metric PAD.