OBJECTIVES

This study aimed to review definitions of digital health and understand their relevance for health outcomes research. Four umbrella terms (digital health, electronic health, mobile health, and telehealth/telemedicine) were summarized in this article.

METHODS

PubMed/MEDLINE, Embase, Cochrane Library, and EconLit were searched from January 2015 to May 2020 for systematic reviews containing key Medical Subject Headings terms for digital health (n = 38) and synonyms of "definition." Independent pairs of reviewers performed each stage of the review, with reconciliation by a third reviewer if required. A single reviewer consolidated each definition for consistency. We performed text analysis via word clouds and computed document frequency-and inverse corpus frequency scores.

RESULTS

The search retrieved 2610 records with 545 articles (20.9%) taken forward for full-text review. Of these, 39.3% (214 of 545) were eligible for data extraction, of which 134 full-text articles were retained for this analysis containing 142 unique definitions of umbrella terms (digital health [n = 4], electronic health [n = 36], mobile health [n = 50], and telehealth/telemedicine [n = 52]). Seminal definitions exist but have increasingly been adapted over time and new definitions were created. Nevertheless, the most characteristic words extracted from the definitions via the text analyses still showed considerable overlap between the 4 umbrella terms.

CONCLUSIONS

To focus evidence summaries for outcomes research purposes, umbrella terms should be accompanied by Medical Subject Headings terms reflecting population, intervention, comparator, outcome, timing, and setting. Ultimately a functional classification system is needed to create standardized terminology for digital health interventions denoting the domains of patient-level effects and outcomes.