Inclusion criteria for EuroSIDA patients in the analysis of four different Health Care Interventions (HCI). cART, combination antiretroviral therapy; baseline = date of enrolment into the EuroSIDA study. Patients for each HCI were selected from 7,366 patients based on the inclusion criteria explained below. HCI 1: all patients who ever started cART (either prior to or after baseline) were included (5859 patients, 4586 on cart at baseline, 1273 start cart after baseline). HCI 2: all EuroSIDA patients, enrolled after 2001 and with a minimum of one follow-up visit (7097). HCI 3: the off cART group included patients who were off cART at baseline and subsequently have not started cART. If patients started cART, they were censored at the time of starting cART. The on cART group included patients who were on cART at baseline or started cART during follow-up (5859 on cart group and 2511 in the off cART group). HCI 4: patients who were on cART for at least 4 consecutive months and had their CD4-cell count and HIV-RNA measured whilst on cART. The first 4 months after each start/change of cART were excluded to ensure that periods when viral suppression would not be expected were not included in the measure of HCI . Follow-up was censored if a patient had not had a HIV-RNA measurement for >6 months and continued from the next available HIV-RNA measurement (5277).