The quality of evidence is downgraded by study limitations (high attrition rates) and publication bias (all studies funded by GlaxoSmithKline, the producer of bupropion XL).
A Cochrane review [Abstract] 1 included 3 studies with a total of 1100 subjects. Overall, moderate-quality evidence indicated that bupropion extended release (XL) was an effective intervention for prevention of recurrence of depressive episodes compared to placebo in people with a history of seasonal affective disorder (SAD) (risk ratio (RR) 0.56, 95% CI 0.44 to 0.72; 3 RCTs, n=1100). However, bupropion XL lead to greater risk of headaches (moderate-quality evidence), insomnia and nausea (both low-quality evidence) when compared with placebo. Numbers needed to treat for additional beneficial outcomes (NNTBs) varied by baseline risks. For a population with a yearly recurrence rate of 30%, the NNTB was 8 (95% CI 6 to 12). For populations with yearly recurrence rates of 50% and 60%, NNTBs were 5 (95% CI 4 to 7) and 4 (95% CI 3 to 6), respectively.
The review found no studies on other second generation antidepressants (SGAs) than bupropion and no studies comparing SGAs with other interventions of interest, such as light therapy, psychological therapies, melatonin or agomelatine.
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