The generalizability of psychotherapy efficacy trials in major depressive disorder: an analysis of the influence of patient selection in efficacy trials on symptom outcome in daily practice.

Background: Treatment guidelines for major depressive disorder (MDD) are based on results from randomized clinical trials, among others in psychotherapy efficacy trials. However, patients in these trials differ from routine practice patients since trials use stringent criteria for patient selection. It is unknown whether the exclusion criteria used in psychotherapy efficacy trials (PETs) influence symptom outcome in clinical practice. We first explored which exclusion criteria are used in PETs. Second, we investigated the influence of commonly used exclusion criteria on symptom outcome in routine clinical practice.

Methods: We performed an extensive literature search in PubMed, PsycInfo and additional databases for PETs for MDD. From these, we identified commonly used exclusion criteria. We investigated the influence of exclusion criteria on symptom outcome by multivariate regression models in a sample of patients suffering from MDD according to the MINIplus from a routine clinical practice setting (n=598). Data on routine clinical practice patients were gathered through Routine Outcome Monitoring.

Results: We selected 20 PETs and identified the following commonly used exclusion criteria: 'a baseline severity threshold of HAM-D≤14', 'current or past abuse or dependence of alcohol and/or drugs' and 'previous use of medication or ECT'. In our routine clinical practice sample of patients suffering from MDD (n=598), presence of 'current or past abuse of or dependence on alcohol and/or drugs' had no significant influence on outcome.'Meeting a baseline severity threshold of HAM-D≤14' and 'previous use of medication or ECT' were associated with better outcome, but the explained variance of the models was very small (R2=2-11%).

Conclusions: The most consistently used exclusion criteria are not a major threat to the generalizability of results found in PETs. However, PETs do somewhat improve their results by exclusion of patients with minor depression and patients who used antidepressants prior to psychotherapy.