IMPORTANCE OF AGE AT INFECTION WITH HIV-1 FOR SURVIVAL AND DEVELOPMENT OF AIDS IN UK HEMOPHILIA POPULATION

Background Greater age at infection with HIV-1 is known to be associat ed with shorter time to development of AIDS, but the size of the diffe rences between people infected in infancy and those infected in old ag e has not been examined in a single large population of patients with death as an endpoint. We, therefore, investigated the role of age at s eroconversion in the entire UK population of haemophiliacs. Methods We studied 1216 HIV-1-infected haemophilia patients in the UK who were r egistered with the National Haemophilia Register and were alive on Jan 1, 1985. Their estimated ages at HIV-1 seroconversion ranged from 8 m onths to 79 years. Findings 10 years after seroconversion 67% (95% CI 64-69) of the population were still alive. Survival was strongly relat ed to age at seroconversion (86% [82-90], 72% [68-76], 45% [39-51], an d 12% [5-21] at 10 years among those patients who seroconverted at age s <15, 15-34, 35-54, and greater than or equal to 55). This steep age- gradient in survival was not explained by deaths expected in the absen ce of HIV infection or by confounding with other factors such as haemo philia type or severity. The age-gradient was steeper for survival tie , time from HIV-1 infection to death) than for time to diagnosis of AI DS, partly because survival after an AIDS diagnosis was poorer in olde r patients, and there was also a substantial increase in mortality amo ng HIV-infected patients who did not satisfy the formal AIDS definitio n and this increase was greater in older patients. Interpretation Age at infection with HIV-1 is a more important determinant of survival th an has previously been appreciated. Age should, therefore, be consider ed in future studies of disease progression, and studies that compare people infected at different ages should provide insight into the biol ogy of the immune response to HIV-1.