Absolute and relative outcomes of psychotherapies for eight mental disorders: a systematic review and meta-analysis

Psychotherapies are first-line treatments for most mental disorders, but their absolute outcomes (i.e., response and remission rates) are not well studied, despite the relevance of such information for health care users, providers and policy makers. We aimed to examine absolute and relative outcomes of psychotherapies across eight mental disorders: major depressive disorder (MDD), social anxiety disorder, panic disorder, generalized anxiety disorder (GAD), specific phobia, post-traumatic stress disorder (PTSD), obsessive-compulsive disorder (OCD), and borderline personality disorder (BPD). We used a series of living systematic reviews included in the Metapsy initiative (www.metapsy.org), with a common strategy for literature search, inclusion of studies and extraction of data, and a common format for the analyses. Literature search was conducted in major bibliographical databases (PubMed, PsycINFO, Embase, and the Cochrane Register of Controlled Trials) up to January 1, 2023. We included randomized controlled trials comparing psychotherapies for any of the eight mental disorders, established by a diagnostic interview, with a control group (waitlist, care-as-usual, or pill placebo). We conducted random-effects model pairwise meta-analyses. The main outcome was the absolute rate of response (at least 50% symptom reduction between baseline and post-test) in the treatment and control conditions. Secondary outcomes included the relative risk (RR) of response, and the number needed to treat (NNT). Random-effects meta-analyses of the included 441 trials (33,881 patients) indicated modest response rates for psychotherapies: 0.42 (95% CI: 0.39-0.45) for MDD; 0.38 (95% CI: 0.33-0.43) for PTSD; 0.38 (95% CI: 0.30-0.47) for OCD; 0.38 (95% CI: 0.33-0.43) for panic disorder; 0.36 (95% CI: 0.30-0.42) for GAD; 0.32 (95% CI: 0.29-0.37) for social anxiety disorder; 0.32 (95% CI: 0.23-0.42) for specific phobia; and 0.24 (95% CI: 0.15-0.36) for BPD. Most sensitivity analyses broadly supported these findings. The RRs were significant for all disorders, except BPD. Our conclusion is that most psychotherapies for the eight mental disorders are effective compared with control conditions, but absolute response rates are modest. More effective treatments and interventions for those not responding to a first-line treatment are needed.