Several recent cohort studies have documented that a proportion of people who have been infected with HIV-1 for 10 years or more remain not only free of AIDS but also free of symptoms.*RF 1-6* Studies of homosexual and bisexual men have found that about half remain free of AIDS 10 years after initially becoming infected,*RF 1-3,5* and one of these studies, the San Francisco City Clinic cohort study, has found that 8% of men infected for between 10 and 15 years remain clinically normal, with only minor immunological and haematological abnormalities.1 Similarly, studies of people infected parenterally through either blood transfusions or anti-haemophilic factors have shown that a substantial proportion remain free of AIDS, even in the oldest age groups, after prolonged HIV-1 infection.4,6

Epidemiologists are now modelling these cohort studies to look further into the future for these patients. In this week's journal Phillips and colleagues from the Royal Free Hospital, London, project 20 and 25 year survival free of AIDS in a large, well characterised cohort of haemophilic men (p 309).4 Using an end point of 50X10⁶ CD4 lymphocytes/l, they project that 25% will remain free of AIDS 20 …