Cookies on this website

We use cookies to ensure that we give you the best experience on our website. If you click 'Accept all cookies' we'll assume that you are happy to receive all cookies and you won't see this message again. If you click 'Reject all non-essential cookies' only necessary cookies providing core functionality such as security, network management, and accessibility will be enabled. Click 'Find out more' for information on how to change your cookie settings.

OBJECTIVE: To develop methods for estimating the incidence of HIV-1 infection among adults from age-specific prevalence data derived in stable endemic conditions. METHODS: Two methods are proposed. The first method is the Cumulative Incidence and Survival Method which treats HIV-1 prevalence at any given age as the cumulative incidence of new infections at each preceding age, adjusted for mortality. A model for age-specific incidence is fitted to the data using maximum likelihood techniques. The other method is the Constant Prevalence Method whereby the incidence of new infections within a time interval (t-r, t) is calculated as the difference, after adjusting for mortality, between observed prevalence levels at two successive age intervals, whose mean ages are r years apart. The two methods were applied to data from Kampala, Uganda. RESULTS: Plausible estimates of age-specific and cumulative HIV-1 incidence were obtained from each of the methods. Estimates of HIV-1 incidence are sensitive to assumptions regarding the length of the survival period after infection and the stability of the epidemic. CONCLUSIONS: Reasonable estimates of HIV-1 incidence can be obtained from prevalence data derived in near-stable conditions. With the Constant Prevalence Method, these conditions may be relaxed if large sample sizes are available and age-reporting is good. The methods proposed could be used in the design and implementation of HIV-1 prevention trials. Cumulative incidence is a better indication of demographic impact than average age-specific incidence.


Journal article


AIDS (London, England)

Publication Date





1689 - 1697


Wellcome Centre for the Epidemiology of Infectious Disease, Zoology Department, Oxford University, UK.


Humans, HIV-1, HIV Infections, Incidence, Age Factors, Adult, Uganda, Statistics as Topic