Twenty-three studies (n=1,365 participants) were included in the review, including 13 randomised controlled trials (RCTs). The quality of the studies was deemed ‘not optimal.’ Several of the studies were not randomised and/or blinded, and there was an absence of, or lack of reporting of, several other key items such as use of antidepressants during STPP (short-term psychodynamic psychotherapy) and treatment integrity checking. Seven studies used intention-to-treat analysis. There was some evidence of publication bias but the authors concluded that it did not significantly influence the results.
STPP versus control groups: Five studies (n=196 participants) compared STPP with waiting list (four studies) or usual care (one study). The pooled effect size was significantly in favour of STPP (0.69, 95% CI 0.30 to 1.08). The level of heterogeneity was low (I2=33%). No subgroup analyses were undertaken for this comparison due to the small number of included studies.
STPP pre- to post-treatment change: Twenty-one studies (n=641 participants) provided information on change in effect size pre- and post-treatment with STPP. STPP was found to significantly improve depression scores post-treatment compared with pre-treatment (1.34, 95% CI 1.13 to 1.55). The level of heterogeneity was moderate (I2 = 60%). Subgroup analyses indicated that similar results were observed in RCTs only and excluding certain outcome measures.
STPP post-treatment to follow-up change: When post-treatment effect sizes were compared with follow-up effect sizes, little difference between time periods were observed, and none of the results were significant.
STPP versus other psychotherapies: Thirteen studies (n=735 participants) compared STPP with a range of therapies including cognitive behavioural therapy, behavioural therapy, cognitive therapy and supportive therapy at post-treatment. Other psychotherapies were found to be statistically superior to STPP in terms of the pooled mean post-treatment effect size difference (-0.30, 95% CI -0.54 to -0.06). The level of heterogeneity was moderate (I2=51%). The superiority of other psychotherapies compared with STPP was also observed at three months and one-year follow-up, but the results were not statistically significant. Subgroup analyses indicated that similar results were observed when considering RCTs only.