ESTIMATES OF DISEASE INCIDENCE IN WOMEN BASED ON ANTENATAL OR NEONATAL SEROPREVALENCE DATA - HIV IN NEW-YORK-CITY

Piecewise constant incidence models were developed to estimate the for ce of infection in women from age-and time-specific antenatal or neona tal seroprevalence data. Differential inclusion of infected women in s ere-surveys compared to uninfected women was taken into account, with respect to both changes in inclusion rate following infection, and cha nges in relative inclusion rate over calendar time. These models were applied to anonymous HIV seroprevalence data collected from neonates b orn to black and Hispanic women in New York City 1988-1992, with incid ence and fertility parameters estimated by maximum likelihood. Estimat es of inclusion rate parameters accorded well with what is known about the natural history of HIV. The data could not distinguish between ad ditive and multiplicative combination of the effects of age and time o n incidence. Incidence was strongly dependent on age with the highest incidence in women aged 20-34 years. There was strong evidence that in cidence had been falling in Hispanic women since 1982-1984. The result s illustrate the extent to which trends in incidence over time may be confounded by changes in the relative inclusion rate of infected and u ninfected women.