Scientific case research in complementary and alternative medicine—A review

SummaryThe description of individual cases is probably the most important didactic tool for teaching in medicine, especially in complementary and alternative medicine (CAM). However, only very rarely is the information provided in traditional single case reports sufficient to answer scientific questions. These reports typically are demonstrations of the solution to a clinical problem. To contribute to scientific discussion single-case research must ask critical questions whose answers are open. Two fundamental questions are: (1) Is my observation reliable? (2) Which factors, other than my treatment, may explain the observed outcome? In this review we will give an introduction to single-case research, as well as present and explain single-case designs as a tool for research and discuss their relevance and applicability for clinical practice in CAM. This review deals exclusively with single-case research on treatment effects and covers observational single-case studies, progressive and repetitive experimental single case designs, n-of-1-RCT, multiple baseline design, best case series and meta-analysis of single-case studies.