Whole Systems Research Methods in Health Care: A Scoping Review

Objectives: This scoping review evaluates two decades of methodological advances made by “whole systems research” (WSR) pioneers in the fields of traditional, complementary, and integrative medicine (TCIM). Rooted in critiques of the classical randomized controlled trial (RCT)'s suitability for evaluating holistic, complex TCIM interventions, WSR centralizes the principle of “model validity,” representing a “fit” between research design and therapeutic paradigm. Design: In consultation with field experts, 41 clinical research exemplars were selected for review from across 13 TCIM disciplines, with the aim of mapping the range and methodological characteristics of WSR studies. Using an analytic charting approach, these studies' primary and secondary features are characterized with reference to three focal areas: research method, intervention design, and outcome assessment. Results: The reviewed WSR exemplars investigate a wide range of multimodal and multicomponent TCIM interventions, typified by wellness-geared, multitarget, and multimorbid therapeutic aims. Most studies include a behavioral focus, at times in multidisciplinary or team-based contexts. Treatments are variously individualized, often with reference to “dual” (biomedical and paradigm-specific) diagnoses. Prospective and retrospective study designs substantially reflect established biomedical research methods. Pragmatic, randomized, open label comparative effectiveness designs with “usual care” comparators are most widely used, at times with factorial treatment arms. Only two studies adopt a double-blind, placebo-controlled RCT format. Some cohort-based controlled trials engage nonrandomized allocation strategies (e.g., matched controls, preference-based assignment, and minimization); other key designs include single-cohort pre–post studies, modified n-of-1 series, case series, case report, and ethnography. Mixed methods designs (i.e., qualitative research and economic evaluations) are evident in about one-third of exemplars. Primary and secondary outcomes are predominantly assessed, at multiple intervals, through patient-reported measures for symptom severity, quality of life/wellness, and/or treatment satisfaction; some studies concurrently evaluate objective outcomes. Conclusions: Aligned with trends emphasizing “fit-for-purpose” research designs to study the “real-world” effectiveness of complex, personalized clinical interventions, WSR has emerged as a maturing scholarly discipline. The field is distinguished by its patient-centered salutogenic focus and engagement with nonbiomedical diagnostic and treatment frameworks. The rigorous pursuit of model validity may be further advanced by emphasizing complex analytic models, paradigm-specific outcome assessment, inter-rater reliability, and ethnographically informed designs. Policy makers and funders seeking to support best practices in TCIM research may refer to this review as a key resource.