Differences in susceptibility to AIDS development: a cohort study of Danish and American homosexual-bisexual men, 1981 to 1995.
We estimated the annual hazard rate for progression to AIDS as defined by the 1987 case definition in HIV-infected members of a cohort of Danish and American homosexual-bisexual men who were observed from 1981 to 1995. Furthermore, we extrapolated the hazard to 25 years based on imputed future time to AIDS. Of 201 HIV-positive subjects, 112 developed AIDS before the end of follow-up. The hazard increased rapidly during the first years following infection, attained a peak of about 15% per year at year 7, and was moderately lower during years 8 through 10. In subsequent analysis, we imputed future time to AIDS in 89 subjects who had not progressed by the end of follow-up by extrapolation from subject-specific CD4 trend lines. A CD4 count of < or = 100 cells/microl was the best surrogate for clinical AIDS. Under this model, the imputed AIDS hazard stabilized at around 8% per year after 10 years. We projected that 13% (95% confidence interval [CI], 8%-19%) of the infected men may remain free from AIDS 25 years after seroconversion. Our direct data suggest that incubation times reflect a mixture of a population that is susceptible to disease progression and has short incubation periods with a group that is relatively resistant. Based on an extrapolation model, > 10% of HIV-infected persons may survive for up to 25 years without developing AIDS.
Danish Epidemiology Science Center, Statens Serum Institut, Copenhagen.
M
M
Melbye
K
K
Begtrup
P S
PS
Rosenberg
R J
RJ
Biggar
J J
JJ
Goedert
K
K
Knudsen
P K
PK
Andersen
D000163:Acquired Immunodeficiency Syndrome / Q000453:epidemiology / Q000276:immunology*; D001727:Bisexuality; D018791:CD4 Lymphocyte Count; D015331:Cohort Studies; D003718:Denmark / Q000453:epidemiology; D018450:Disease Progression; D004198:Disease Susceptibility; D018572:Disease-Free Survival; D004219:District of Columbia / Q000453:epidemiology; D005500:Follow-Up Studies; D006679:HIV Seropositivity / Q000453:epidemiology / Q000276:immunology*; D006716:Homosexuality; D006801:Humans; D008297:Male; D009519:New York City / Q000453:epidemiology; D011336:Probability; D016016:Proportional Hazards Models; D013997:Time Factors