To detect a difference of 20%, in a one-sided model, with an alpha of 5% and power of 80%, 152 depressed persons, 76 to each group, will be required for the study. A design effect of 2.42 was estimated. After applying the design effect the sample needed increased to 368 depressed persons. Considering a retention rate of approximately 85%, 434 depressed cases will be needed required for the study, hence 109 cases in each of the 4 primary health care clinics.