Photoplethysmography technology use in smart devices for early diagnosis of arterial hypertension: a systematic review

Background: According to the World Health Organisation (WHO), 1 in 4 men and 1 in 5 women have arterial hypertension (AH). It is important to diagnose AH early and constantly monitor blood pressure (BP). We assess the diagnostic accuracy of AH detection using smart devices with photoplethysmography (PPG) and seek to provide guidance from current evidence to clinicians about the value and limitations of their potential use to early diagnose this chronic disease. Material and methods: This systematic review of Medline, Google Scholar, and PubMed databases was conducted according to the PRISMA guidelines. All publications examining any type of AH detection using PPG in smart devices were evaluated. Study quality was assessed using the QUADAS-2 risk of bias tool. Results: The search strategy identified a total of 705 publications, of which 9 studies were included in the systematic review. Of the 9 studies included, 2 used Samsung Galaxy smartphones, and 7 used wearable watch-like devices. A sphygmomanometer was used as a reference standard in all studies. Conclusion: The current evidence base consists of small, biased, and low-quality studies which are insufficient to advise clinicians on the true value of PPG devices for AH detection. Further research is required with reference standards, standardized validation, and transparent algorithms for PPG technology to be used as a valid tool for early AH diagnosis