Weighing the Evidence: What Is Revealed by 100+ Meta-Analyses and Systematic Reviews of Religion/Spirituality and Health?

This chapter reviews the more than 100 meta-analyses and systematic reviews of relations between religion/spirituality (R/S) and health that have been published in refereed journals, a far larger number than is generally recognized. The 118 published reviews identified by 2017 were categorized as quantitative meta-analyses (n = 33), qualitative meta-syntheses (n = 7), meta-analyses of case studies (n = 1), or simple systematic reviews (n = 77). They addressed a wide range of substantive topics relevant to every major public health subfield, and incorporated a mean of 33.5 studies per review. Collectively authored by more than 200 distinct individuals, the reviews were published in 83 different journals, 20 in the category of public health. Multiple reviews were published by 14 journals, a majority possessing impact factors above 2.0. Reviewing empirical studies of R/S-health is clearly a very broad-based enterprise not limited to a few individuals or journals. Collectively, the reviews greatly strengthen the case, based on Hill’s criteria, that R/S exerts a causative influence on health. The case for causal influence may now be compelling, and in most cases R/S involvement is associated with better health, although negative associations also exist. Further investigation is warranted to explore the possibility that R/S is a “fundamental cause” of health that maintains an association even when intervening mediating pathways change. This possibility is consistent with the dynamic understandings of R/S presented elsewhere in this volume.