The use of experimental vignette studies to identify drivers of variations in the delivery of health care: a scoping review

BACKGROUND: Identifying how unwarranted variations in healthcare delivery arise is challenging. Experimental vignette studies can help, by isolating and manipulating potential drivers of differences in care. There is a lack of methodological and practical guidance on how to design and conduct these studies robustly. The aim of this study was to locate, methodologically assess, and synthesise the contribution of experimental vignette studies to the identification of drivers of unwarranted variations in healthcare delivery. METHODS: We used a scoping review approach. We searched MEDLINE, Embase, Web of Science and CINAHL databases (2007–2019) using terms relating to vignettes and variations in healthcare. We screened title/abstracts and full text to identify studies using experimental vignettes to examine drivers of variations in healthcare delivery. Included papers were assessed against a methodological framework synthesised from vignette study design recommendations within and beyond healthcare. RESULTS: We located 21 eligible studies. Study participants were almost exclusively clinicians (18/21). Vignettes were delivered via text (n = 6), pictures (n = 6), video (n = 6) or interactively, using face-to-face, telephone or online simulated consultations (n = 3). Few studies evaluated the credibility of vignettes, and many had flaws in their wider study design. Ten were of good methodological quality. Studies contributed to understanding variations in care, most commonly by testing hypotheses that could not be examined directly using real patients. CONCLUSIONS: Experimental vignette studies can be an important methodological tool for identifying how unwarranted variations in care can arise. Flaws in study design or conduct can limit their credibility or produce biased results. Their full potential has yet to be realised. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12874-021-01247-4.