Annual partnership dissolution rates by HIV status of the couple, and other parameter values.

Notes: The annual partnership dissolution rates are derived from Porter et al. [1] and Grinstead et al. [2]. From Porter et al. we take the 40-month dissolution probability from Table 5 and adjust for the fraction of women that are widowed and the duration to obtain an annual dissolution rate. More specifically, we divide by the fraction not widowed and then solve for the annual rate, a, such that 1-(1-a)40/12 = 1-(40-monthly rate). From Grinstead et al. we take the probability of a “break-up of a sexual relationship” and the probability of a “break-up of a marriage” after 7.3 months from Table 3 and adjust it similarly to obtain an annual dissolution rate. Neither of these studies contains sufficient detail to report the sample sizes on which these rates are based. The sample in Grinstead et al. is particularly small and it is unclear whether the numbers that are reported take the individual or couple as the unit of analysis. Carpenter et al. [3] also report dissolution rates by the serostatus of both spouses (with similar conclusions), but again based on a very small sample.