Presentation and Analysis of the Online Evidence Gap Map, “Clinical Effectiveness of Homeopathy”

This study presents and analyzes the content of an online Evidence Gap Map (EGM), "<i>Clinical Effectiveness of Homeopathy, 1st Edition</i>", which graphically represents evidence from systematic reviews (SRs) of human clinical trials in homeopathy that were published from 1991 to 2021. The EGM was built according to the guidelines of the International Initiative for Impact Evaluation (3ie), adapted for complex interventions, to represent visually relevant evidence and research gaps.The interventions, classified as rows, are characterized in the EGM not only by the homeopathic therapeutic strategy but also by individual medicines and potencies. The outcomes are listed in columns. The associations between both are represented by "bubbles" that refer to the corresponding SRs and whose colors indicate their quality level.From 239 citations identified, 51 SRs underwent complete characterization for the final construction of the EGM. A further in-depth quality analysis of each SR was performed to list the studied intervention/outcome associations described in each mentioned trial. At this step, those trials considered to have a high risk of bias by the authors of each SR were excluded from the EGM inputs.The methodological quality of each of the EGM's SRs was evaluated using the AMSTAR-2 criteria for level of confidence in an SR's results. Intervention-outcome associations were categorized into one of five effects of a homeopathic intervention: <i>positive</i>, <i>potentially positive</i>, <i>ineffective</i>, <i>inconclusive</i>, or <i>negative</i>.The EGM presents research evidence across a wide range of medical conditions, with substantial heterogeneity of homeopathic interventions and clinical outcomes. Forty-two of the 51 SRs yielded inconclusive findings. AMSTAR-2 analysis identified seven high-quality SRs, in which reliable primary studies presenting positive or potentially positive results for different categories of homeopathy are cited and related to specific clinical conditions: fibromyalgia, otitis media, diarrhea, respiratory infections, menopausal syndrome, irritable bowel syndrome, and attention deficit hyperactivity disorder in children.The EGM "<i>Clinical Effectiveness of Homeopathy, 1st Edition</i>" presents visually relevant research evidence that is scattered across a large number of medical conditions, showing substantial heterogeneity of homeopathic interventions, clinical outcomes, and research quality. To enhance the precision and relevance of future research, we recommend that the individualized homeopathic approach under investigation be standardized to the greatest extent feasible, and to use measures of well-being and quality of life as primary outcomes.