Validity of resting heart rate derived from contact-based smartphone photoplethysmography (PPG) compared with electrocardiography (ECG): Protocol for a Systematic Review and Meta-Analysis

Objective To synthesise quantitative evidence on the validity of photoplethysmography (PPG) derived from mobile devices (i.e. smartphones) for the assessment of heart rate (HR) compared to the gold standard electrocardiogram (ECG). Introduction Mobile health (mHealth), the use of mobile devices for promotion or measurement of health is on the rise. Smartphone cameras can perform photoplethysmography (PPG) for the assessment of heart rate (HR) and other cardiac cycle characteristics. However, rigorous validity is necessary before smartphone measurement of PPG can be utilized for healthcare provision. There is a pervasive belief that HR-PPG is analogous to HR-ECG, and herein we will provide an updated systematic review and meta-analysis to support or challenge this supposition. Inclusion criteria This review will include studies that investigate the correlation coefficient between of resting heart rate (RHR) acquisition from PPG utilizing contact-based smartphone devices versus ECG as the gold standard, Studies will be excluded if they (a) do not use PPG utilizing contact-based smartphone devices (b) compare PPG to another collection method other than ECG, or (c) are review articles or case studies. Methods A comprehensive literature search will be conducted in CINAHL Ultimate, MEDLINE, ScienceDirect, and Scopus using a search strategy developed in collaboration with the research team. All retrieved citations will be imported into Rayyan for screening and data management. A minimum of two independent reviewers will conduct the title and abstract screening, followed by two independent reviewers who will perform full-text screening and data extraction. All stages will be guided by predefined inclusion and exclusion criteria, which will be pilot tested to ensure consistency and reliability. Any discrepancies will be resolved through discussion with a third reviewer or during a research team meeting. Intra-rater reliability will be quantified at the title and abstract stage, and the full-text review stage using Cohen’s Kappa. To ensure clarity and consistency in the presentation of study characteristics and findings, both narrative synthesis and tabular formats will be employed. Review registration: https://doi.org/10.17605/OSF.IO/83V7A