To the Editor: Drs Leichsenring and Rabung1 reported that long-term psychodynamic psychotherapy (LTPP) is more effective than shorter forms of psychotherapy for complex mental disorders based on a between-group effect size of 1.8 from 7 comparative trials that they meta-analyzed. The authors did not indicate that they were concerned about this and other surprisingly large effect sizes they reported.
Thombs BD, Bassel M, Jewett LR. Analyzing Effectiveness of Long-term Psychodynamic Psychotherapy. JAMA. 2009;301(9):930-933. doi:10.1001/jama.2009.177