Asynchronous Telemedicine: A Systematic Literature Review

Background: Asynchronous telemedicine (ATM), which describes telemedical interaction between a patient and provider where neither party communicates simultaneously, is an important telemedicine modality that is seeing increased use. In this article, we summarize the published peer-reviewed literature specifically related to ATM to (1) identify terms or phrases that are used to describe ATM, (2) ascertain how this research has thus far addressed the various aspects of the quadruple aim of medicine, and (3) assess the methodological rigor of research on ATM. We also divided the literature into pre- and post-COVID-19 onset periods to identify potential variations in the literature between these two periods. Methods: This systematic literature review follows the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The literature search, utilizing multiple databases and applying inclusion and exclusion criteria, initially produced 2624 abstracts for review. De-duplication and screening ultimately yielded 104 articles for data extraction. Results: “Store-and-forward” and variations of “e-visit” were the most frequently used alternative terms for ATM. Care quality was the most frequently addressed aspect of the Quadruple Aim of Medicine—more than double any other category—followed by patient satisfaction. We separated cost of care into two categories: patients' cost of care and providers' cost to provide care. Patient cost of care was the third most addressed aspect of the Quadruple Aim of Medicine followed by provider well-being and provider's cost to provide care. Methodological rigor of the studies was also addressed, with only 2 quantitative studies ranked “Strong,” 5 ranked “Moderate,” and 97 ranked “Weak.” Qualitative studies were generally acceptable but struggled methodologically with accounting for all participants and articulation of results. Conclusions: Although “store-and-forward” is somewhat more frequently used in the studies included in this review, variants of “e-visit,” are growing in recent usage. Given the relative newness of modality, it is not surprising that quality of care is the most researched aspect of the Quadruple Aim of Medicine in ATM research. We anticipate more balance between these areas as research in this field matures. Primary areas of research need currently relate to practitioners—specifically their costs of providing care and well-being. Finally, future ATM research needs to address research challenges of selection bias and blinding in quantitative studies and improved participant tracking and articulation of both study design and results in qualitative studies.