Concealment of the patient allocation to study arms was done to avoid both conscious and unconscious selection of patients into the study. The research assistants assessed the eligibility of the patients, sought their consent for study participation, and then the enrollment officer with the sealed trial randomization envelopes let the patient pick the envelope containing the study arm. To further ensure unbiased allocation of patients to study arms, I used varying block size, specifically size 6 so that the recruiting officer does not guess which study arm follows (Concealment through sequence generation). I used a computer-generated allocation sequence with a randomization ratio of 1:1, to PSCB or SOC We collected data using interviewer-administered questionnaires and HIV clinic forms. Patients received a questionnaire at baseline, six months and 12 months follow up visits. All visits were conducted at the HIV clinics. At baseline visit, we collected socio-demographic information including level of education, occupation, marital status, distance to the HIV clinic, willingness to select a buddy as well as readiness to disclose HIV status to a buddy. At both the 6 and 12 month follow up visits, information on continued possession of a buddy, change or loss of a buddy, relationship and perceived helpfulness of their buddy (if in intervention arm), self-reported adherence to clinic appointments and cotrimoxazole, quality of life and sexual behaviors including sexual activity, condom use and number of sexual partners (marital and non-marital) were collected. As per clinic schedules, patients were required to come to the clinic for cotrimoxazole refills at least 3 monthly and to have a blood draw for CD4 testing as follows: at 3 months if previous CD4 count was 251-350 cells/ul or after six months if CD4 was greater than 350 cells/ul. Routine clinic data, collected on clinic forms included patient visit data (visit date, number of cotrimoxazole pills dispensed, blood samples taken for testing), health status (e.g. opportunistic infections diagnosed, Karnofsky score, WHO staging) and laboratory results, including CD4 counts and any other investigations as clinically indicated. Blood for CD4 testing was collected from participants at the various community clinics and transported to the central Rakai Health Sciences Program laboratory in Kalisizo.CD4 counts were assessed by flow cytometry using a FACS Calibur (Becton Dickinson, San Jose, CA, USA).