The natural history of human immunodeficiency virus infection: a five year study in a London cohort of homosexual men.

Progression rates from asymptomatic to symptomatic Human Immunodeficiency Virus (HIV) infection according to the CDC classification were prospectively studied in a cohort of 172 seropositive homosexual and bisexual men. The median follow-up time was 4 years. The progression from data of entry to the study to any group IV disease was 56% (SE 7%) at 5 years. However, the progression from an estimated date of seroconversion to any group IV disease was 36% (SE 4%) at 5 years. This was more than double the progression rate to AIDS-14% (SE 3%) at 5 years calculated in the same way. There were no differences in progression to AIDS from group IV A (systemic symptoms such as unexplained fever, weight loss or persistent diarrhoea) and group IV C-2 (oral candida or oral hairy leukoplakia). Progression rates to AIDS were significantly lower (p = 0.02) in patients who were under 25 years of age at entry than in those over 25. A review of progression rates to AIDS among homosexual cohorts shows that they tend to be higher than in cohorts of haemophiliac patients, in the early stage of infection. However, when Pneumocystis carinii pneumonia is the outcome measure, progression rates in all studies are remarkably similar.