RESUMEN
BACKGROUND: Despite the extensive literature assessing associations between religiosity/spirituality and health, few studies have investigated the clinical applicability of this evidence. The purpose of this paper was to assess the impact of religious/spiritual interventions (RSI) through randomized clinical trials (RCTs). METHOD: A systematic review was performed in the following databases: PubMed, Scopus, Web of Science, PsycINFO, Cochrane Collaboration, Embase and SciELO. Through the use of a Boolean expression, articles were included if they: (i) investigated mental health outcomes; (ii) had a design consistent with RCTs. We excluded protocols involving intercessory prayer or distance healing. The study was conducted in two phases by reading: (1) title and abstracts; (2) full papers and assessing their methodological quality. Then, a meta-analysis was carried out. RESULTS: Through this method, 4751 papers were obtained, of which 23 remained included. The meta-analysis showed significant effects of RSI on anxiety general symptoms (p < 0.001) and in subgroups: meditation (p < 0.001); psychotherapy (p = 0.02); 1 month of follow-up (p < 0.001); and comparison groups with interventions (p < 0.001). Two significant differences were found in depressive symptoms: between 1 and 6 months and comparison groups with interventions (p = 0.05). In general, studies have shown that RSI decreased stress, alcoholism and depression. CONCLUSIONS: RCTs on RSI showed additional benefits including reduction of clinical symptoms (mainly anxiety). The diversity of protocols and outcomes associated with a lack of standardization of interventions point to the need for further studies evaluating the use of religiosity/spirituality as a complementary treatment in health care.