Clinical research on homeopathic medicinal products: Protocol template for a series of systematic reviews

BackgroundThe clinical benefits of homeopathic medicinal products (HMPs) used in anthroposophic medicine and homeopathy remain a topic of debate. Systematic reviews (SRs) including meta-analyses (MAs), that assess the literature in line with scientific standards and account for the holistic nature of the intervention and its delivery, are missing for many health conditions.ObjectiveTo conduct SRs with or without MAs on the effectiveness, efficacy and safety of HMPs for selected patient populations based on health conditions. This includes a pluralistic approach with the assessments of internal, model and external validity as well as quality of reporting and the exploration of intervention complexity and research gaps.MethodsThis protocol follows PRISMA-P. We will conduct a comprehensive literature search including the HOMIS database, MEDLINE, EMBASE, CINAHL, Cochrane Central Register of Controlled Trials, AMED, LILACS, topic-specific sources, citation indices, trial registers and grey literature including preprint servers. Eligible studies will need a prospective, longitudinal design covering randomized controlled trials and non-randomized comparative studies, published in in various languages, to evaluate HMPs interventions on efficacy, effectiveness and safety in health conditions preselected in consensus expert panels. All types of patients, homeopathic interventions, co-interventions, therapeutic goals (prevention/treatment), and comparison groups (e.g. active, placebo, no treatment) will be included. Research questions, outcome selection and dissemination are developed with consideration of the patient perspective.Each of the SRs will be managed by a multidisciplinary team comprising methodologists, homeopaths, and physicians with expertise in the specific indications under review. This team will determine the research questions and hierarchy of outcome parameters depending on the health condition. A multi-disciplinary advisory group will oversee this work. Risk of bias will be assessed using ROB-2 and ROBINS-I. Reporting quality, model validity, and generalizability will be evaluated from a homeopathic perspective using CATHIS. Intervention complexity will be analyzed with an adapted iCAT_SR.If a meta-analysis is not feasible, a narrative synthesis following SWiM will be conducted. If a meta-analysis is possible, we will examine the above objectives quantitatively. The certainty of evidence will be assessed according to GRADE. DiscussionThis series of SRs and MAs investigates the effects of HMPs provided as complex interventions in healthcare. It aims to establish an evidence base regarding the efficacy, effectiveness and safety of HMPs for prevention and therapy of health conditions in selected patient populations. Internal and model validity, quality of reporting, generalizability, possible effect moderators, and sources of heterogeneity are components that may contribute to building a more comprehensive picture of the homeopathy studied and may help to understand under which circumstances HMPs result in clinical benefits. Additionally, the SRs may help to identify research gaps or shortcomings and enhance the reliability of future studies.