[Multicenter Cohort of Patients with HIV Infection in the Madrid South-eastern Metropolitan Crown (COMESEM): Basis, Organization and Initial Results]

Background: In order to evaluate changes related to the effect of new anti-retroviral agents and preventive programs, cohort studies of patients with HIV in our environment are needed.

Methods: Cohort study of patients diagnosed of HIV infection in the five hospitals included in the Madrid metropolitan south-eastern crown (COMESEM), which attend a population of 1,300,000 inhabitants.

Results: A total of 5,532 patients had been recruited until August 2001 (with a follow-up of 34,227 patients-year). The male/female ratio was 3/1. As for the transmission mechanism, 72.9% were parenteral drug users (PDU), 13.7% heterosexuals (HTX) and 8% of males having sex with males (MSM). The maximal figure of diagnosis per year corresponded to 1991 for PDU, 1993 for MSM and 1995 for heterosexuals. A decline in the number of diagnosed patients was observed for all groups, but MSM showed an increase in the year 2001 for the first time. Notably, among HTX, a growing and sustained trend was observed of patients not born in Spain (0% in 1993 and 50% in 2001; p < 0.001).

Conclusions: Establishing a large cohort of HIV infected patients based upon medium-sized hospitals is possible. The analysis of data derived from this cohort allows the early detection of changes in the clinical and epidemiological profile of HIV infection.