A Cochrane review included 3 RCTs and 3 observational studies with 265 participants with seasonal affective disorder. The trials were between 5 and 8 weeks of duration. The RCTs were included for efficacy analysis. For adverse effects 2 of these RCTs and the observational studies (including 15 - 26 participants) were included with a total of 225 participants. All participants in the studies met DSM (Diagnostic and Statistics Manual of Mental Disorders) criteria for seasonal affective disorder. The average age was approximately 40 years and 70% of the participants were female.
• Fluoxetine vs. placebo (one trial, n=68): fluoxetine was not significantly more effective than placebo in achieving clinical response (RR 1.62, 95% CI 0.92 to 2.83).
• Fluoxetine vs. light therapy (two trials, n=136): The meta-analysis of the results showed fluoxetine and light therapy to be approximately equal in treating seasonal depression (RR of response 0.98, 95% CI 0.77 to 1.24, RR of remission 0.81, 95% CI 0.39 to 1.71).
• Adverse effect data was available for fluoxetine, escitalopram, duloxetine, reboxetine and light therapy (2 RCTs and 3 non-RCTs, n=225). Of the participants receiving second-generation antidepressants, between 22% and 100% had an adverse effect. Of them, between 15% and 27% withdrew from the studies because of adverse effects.
Comment: The quality of the evidence is downgraded by study quality (inadequate allocation concealment, high attrition rate, short follow-up time), imprecise results (limited study size for each comparison) and indirectness (patient-important outcomes scarcely available, few results on any parameters).