Reducing HIV transmission risk by increasing serostatus disclosure: a mathematical modeling analysis

Abstract

Persons living with HIV infection are encouraged to disclose their HIV-positive serostatus to prospective sex partners to decrease the likelihood of unsafe sex and HIV transmission. However, the effectiveness of serostatus disclosure as a preventive measure is not known. We developed a mathematical framework for assessing the HIV transmission risk reduction effectiveness of serostatus disclosure, examined how increasing the disclosure rate affects the transmission risk reduction effectiveness of disclosure, and explored the interaction between condom use and disclosure effectiveness. Under base-case assumptions, serostatus disclosure reduced the risk of HIV transmission by between 17.9% and 40.6% relative to no disclosure. Increasing the disclosure rate from the base-case value of 51.9-75.7% produced a 26.2-59.2% reduction in risk. The findings of this modeling study strongly support intervention efforts to increase both serostatus disclosure and condom use by persons living with HIV.

Fig. 1

Risk reduction effectiveness of serostatus disclosure as a function of the proportion of prospective sex partners who agree to intercourse after learning the HIV-positive partner's serostatus. The base-case results assumed a 77.6% post-disclosure condom use rate and a 72.7% non-disclosure condom use rate. Disclosure effectiveness is maximal when condoms are used consistently during post-disclosure sex (K = 100%) but not at all in the absence of disclosure (C = 0%), and is minimal when condom use is no more likely following disclosure than in the absence of disclosure (K = C)

Fig. 2

Proportion reduction in risk obtained by increasing disclosure from a baseline of 0% or 51.9% to indicated post-intervention values assuming that half of prospective sex partners agree to intercourse following disclosure. In the maximum risk reduction scenario the post-disclosure condom use rate is K = 100% and the non-disclosure condom use rate is C = 0%; in the base-case scenario, K = 77.6% and C = 72.7%; and in the minimum risk reduction scenario the post-disclosure condom use rate equals the non-disclosure condom use rate (i.e., K = C). The corresponding disclosure effectiveness values are 85.5% (maximum), 56.4% (base-case), and 50.0% (minimum)

Fig. 3

Proportionate risk reduction produced by a hypothetical intervention that increases the disclosure rate from D₀ = 51.9% to a higher rate D₁, and the post-disclosure and non-disclosure condom use rates from K₀ = 77.6% and C₀ = 72.7% to K₁ = 89.9% and C₁ = 76.6%. The 75.7% disclosure rate is from Niccolai et al.'s (1999) study, whereas the 51.9% baseline disclosure rate is from Marks and Crepaz (2001)