A Finnish Community Randomized Psychotherapy Effectiveness Study for Major Depression

Patients having signs of depression referred to Lohja area secondary level psychiatric clinics were assessed to the trial. After verification the diagnosis of Major Depressive Disorder (MDD) they were informed of the study. Consented patients were randomized to three study arms.

Baseline clinical demographics was collected. Psychotherapeutic treatment was implemented by specially trained therapists and the study data was collected by trained psychiatrists who were blinded to the therapy model patients has received.Primary outcome measure was 17-item Hamilton Depression Rating Scale (HAMD) and secondary outcome measures were Clinical Global Impression scale (CGI), Social and Occupational Functioning Assessment Scale ( SOFAS), Social Adaptation Scale ( Finnish translation JES) and Quality of Life assessment ( a Finnish validated questionnaire 15-D).The total of sick leave days and number of possible disability pensions in a year were assessed as well.

Assessments were implemented at the beginning, at 1,5 month, at 3 months ( which was the end of active treatment of short-term psychotherapies), at 6 months and at 12 months.

The primary assessment was planned to carry out using tests of group comparison. Sample size of 32 and 32 achieve 91% power to detect a clinically meaningful difference with a significance level (alpha) of 0.01 using two-sided two-sample t-test. Baseline differences in demographic variables and the depression measurement across the three treatment groups were tested using chi-square tests and analysis of variance.Likelihood-based inference using linear mixed models were employed to analyze treatment effects, focusing on the time x treatment interaction. Separate analyses assessed IPT-TAU and PeGT-TAU comparisons. All statistical analyses were performed using R. The aim of this study was to get a total of 140-160 patients, about 50 patients on one group.The final number of patients showed to be 134.

The statistical calculation was intent-to-treat model with consideration to missing data, because in this kind of natural setting notable attrition was assumed. The training of the therapists and researchers and quality control during assessments was considered and personnel was supervised throughout the study.