A Cochrane review included 8 studies with a total of 266 subjects. These studies demonstrated that patients receiving any variant of cognitive behavioural treatment exhibited significantly fewer symptoms post-treatment than those receiving treatment as usual (SMD -1.24, 95% CI -1.61 to -0.87, I² test for heterogeneity 33.4%). Different types of cognitive and/or behavioural treatments showed similar differences in effect when compared with treatment as usual. The overall treatment effect appeared to be influenced by differences in baseline severity.
Comment: The quality of evidence is downgraded by study quality; inadequate or unclear allocation concealment.