Editorial
Copyright ©The Author(s) 2015. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Meta-Anal. Feb 26, 2015; 3(1): 1-3
Published online Feb 26, 2015. doi: 10.13105/wjma.v3.i1.1
Why meta-analyses are important for complementary and alternative medicine research
Holger Cramer
Holger Cramer, Department of Internal and Integrative Medicine, Kliniken Essen-Mitte, Faculty of Medicine, University of Duisburg-Essen, 45276 Essen, Germany
Author contributions: Cramer H solely contributed to this editorial.
Supported by Rut- and Klaus-Bahlsen Foundation, Germany.
Conflict-of-interest: The supportive foundations had no influence on the content of this editorial.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Correspondence to: Dr. Holger Cramer, PhD, MSc, Department of Internal and Integrative Medicine, Kliniken Essen-Mitte, Faculty of Medicine, University of Duisburg-Essen, Am Deimelsberg 34a, 45276 Essen, Germany. h.cramer@kliniken-essen-mitte.de
Telephone: +49-201-17425015 Fax: +49-201-17425000
Received: October 20, 2014
Peer-review started: October 20, 2014
First decision: November 27, 2014
Revised: December 3, 2014
Accepted: December 29, 2014
Article in press: December 31, 2014
Published online: February 26, 2015
Processing time: 181 Days and 10.7 Hours
Abstract

Complementary and alternative medicine (CAM) is defined as a group of interventions that are not generally considered part of conventional medicine. This definition already implies that CAM interventions are often not systematically studied; and the research evidence from single trials on CAM is often limited by small sample sizes, unclear methodology, and inadequate statistics. As a result, both, significant and insignificant results are often hard to interpret based on single trials. Summarizing the evidence from single CAM trials, qualitative systematic reviews still have to deal with the same problems as individual trials as they can only rely on the original reports. Thus, effects of CAM interventions are often underestimated or overestimated based on single trials or qualitative systematic reviews. While meta-analyses still are limited by the methodological shortcomings of the included studies, a well-conducted meta-analysis can deal with two common problems of CAM trials: inadequate statistics that rely on within-group comparisons and small underpowered sample sizes. Although large and high quality trials are urgently needed for most CAM interventions, funding often is limited. Until higher quality research is available, meta-analyses provide a useful tool to investigate the actual level of evidence of currently published CAM trials. This editorial presents examples of meta-analyses in the field of CAM and discusses how they contribute to the consolidation of evidence.

Keywords: Complementary therapies; Meta-analysis; Review; Randomized controlled trial; Bias

Core tip: The research evidence from single trials on complementary and alternative medicine (CAM) is often limited by small sample sizes, unclear methodology, and inadequate statistics. Qualitative systematic reviews still have to deal with the same problems as individual trials as they can only rely on the original reports. While meta-analyses still are limited by the methodological shortcomings of the included, they can deal with two common problems of CAM trials: inadequate statistics that rely on within-group comparisons and small underpowered sample sizes.