title: More than the sum of its parts: meta-analysis and its potential to discover sources of heterogeneity in psychosomatic medicine.
abstract: Meta-analyses may contribute to more reliable knowledge about the existence of certain relations in the area of psychosomatic research. Surprisingly, the increasing popularity of meta-analysis is not reflected in the number of meta-analyses of observational studies published in Psychosomatic Medicine. This may be due to the specific difficulties that apply to meta-analyses of observational research. The aim of this paper is to provide a nontechnical overview of the principles of meta-analysis applied to observational research. We will highlight general principles of meta-analysis and discuss the major threats to its validity, with an emphasis on its specific merits and pitfalls for psychosomatic research, using several examples. We conclude that meta-analysis is a relatively simple technique, leaving little reason for not routinely applying it when performing a systematic review. An adequately conducted meta-analysis may not only provide a summary estimate of a certain association, but it has additional value in discovering relevant confounders, mediators, and moderators, as well as identifying areas of research that require more attention.
authors.affiliation: Interdisciplinary Center for Psychiatric Epidemiology, CC72, University Medical Center Groningen, University of Groningen, Hanzeplein 1, 9700 RB, Groningen, Netherlands.
authors.forename: Lineke M
authors.initials: LM
authors.lastname: Tak
authors.forename: Anna
authors.initials: A
authors.lastname: Meijer
authors.forename: Andiappan
authors.initials: A
authors.lastname: Manoharan
authors.forename: Peter
authors.initials: P
authors.lastname: de Jonge
authors.forename: Judith G M
authors.initials: JG
authors.lastname: Rosmalen
mesh_terms: D035843:Biomedical Research / Q000379:methods* / Q000706:statistics & numerical data; D002986:Clinical Trials as Topic; D006801:Humans; D015201:Meta-Analysis as Topic; D011611:Psychosomatic Medicine / Q000379:methods / Q000706:statistics & numerical data*; D016032:Randomized Controlled Trials as Topic; D015203:Reproducibility of Results; D012196:Review Literature as Topic