Heterosexual partner acquisition rates in the Australian population.

The rate of partner acquisition in a population is an important parameter when constructing epidemiological models of sexually transmissible infections. We have analysed the results of a survey of the sexual behaviour of the Australian population to estimate how many people have acquired no new partner, one, two or at least three new partners in the past year, and hence estimated heterosexual partner acquisition rates for the population by gender and age band. Partner acquisition rates are ~0.5 new partners per year for 16- to 19-year-olds, peak at ~0.7 in the 20- to 24-year-old age band, and then decline steadily with age to ~0.2 per year. In all age bands, there are more male respondents reporting three or more new partners in the last year than what is consistent with the rest of the data, which could be interpreted as evidence of an additional population stratum characterised by higher partner acquisition rates.