Second‐generation antidepressants for preventing seasonal affective disorder in adults

Background Seasonal affective disorder (SAD) is a seasonal pattern of recurrent major depressive episodes that most commonly occurs during autumn or winter and remits in spring. The prevalence of SAD ranges from 1.5% to 9%, depending on latitude. The predictable seasonal aspect of SAD provides a promising opportunity for prevention. This review ‐ one of four reviews on efficacy and safety of interventions to prevent SAD ‐ focuses on second‐generation antidepressants (SGAs). Objectives To assess the efficacy and safety of SGAs (in comparison with other SGAs, placebo, light therapy, melatonin or agomelatine, psychological therapies or lifestyle interventions) in preventing SAD and improving patient‐centred outcomes among adults with a history of SAD. Search methods We searched Ovid MEDLINE (1950‐ ), Embase (1974‐ ), PsycINFO (1967‐ ) and the Cochrane Central Register of Controlled Trials (CENTRAL) to 19 June 2018. An earlier search of these databases was conducted via the Cochrane Common Mental Disorders Controlled Trial Register (CCMD‐CTR) (all years to 11 August 2015). Furthermore, we searched the Cumulative Index to Nursing and Allied Health Literature, Web of Science, the Cochrane Library, the Allied and Complementary Medicine Database and international trial registers (to 19 June 2018). We also conducted a grey literature search and handsearched the reference lists of included studies and pertinent review articles. Selection criteria For efficacy, we included randomised controlled trials (RCTs) on adults with a history of winter‐type SAD who were free of symptoms at the beginning of the study. For adverse events, we planned to include non‐randomised studies. Eligible studies compared a SGA versus another SGA, placebo, light therapy, psychological therapy, melatonin, agomelatine or lifestyle changes. We also intended to compare SGAs in combination with any of the comparator interventions versus placebo or the same comparator intervention as monotherapy. Data collection and analysis Two review authors independently screened s and full‐text publications, extracted data and assessed risk of bias of included studies. When data were sufficient, we conducted random‐effects (Mantel‐Haenszel) meta‐analyses. We assessed statistical heterogeneity by calculating the Chi2 statistic and the Cochran Q. We used the I2 statistic to estimate the magnitude of heterogeneity. We assessed publication bias by using funnel plots.We rated the strength of the evidence using the