Table 1: Bernoulli formula, estimated risk parameters, and self-reported behaviors used to create composite HIV risk outcome measure (HIVRISK).

Bernoulli mathematical formula

HIVRISK =

Estimated HIV risk parametersBase estimatesSource

: probability that primary male sex partner is HIV infected
: probability that a secondary sex partner is HIV infected0.15
: probability that an injection partner is HIV infected0.25
: per contact probability of HIV transmission (infectivity) for anal sex.017[43, 44]
: per contact HIV transmission for male-to-female vaginal sex.0008[43]
: per act HIV transmission for receptive syringe sharing.0074[45, 46]
: condom failure rate.10[44]

Measured self-reported risk behaviors

mvu: number of acts of condom unprotected vaginal intercourse with primary male partner
mvp: number of acts of condom protected vaginal intercourse with primary male partner
mau: number of acts of condom unprotected anal intercourse with primary male partner
map: number of acts of condom protected anal intercourse with primary male partner
mij: number of times receptive syringe sharing with primary male partner
svu: number of acts of condom unprotected vaginal intercourse with secondary sex partner
svp: number of acts of condom protected vaginal intercourse with secondary sex partner
sau: number of acts of condom unprotected anal intercourse with secondary sex partner
sap: number of acts of condom protected anal intercourse with secondary sex partner
sij: number of times receptive syringe sharing with secondary partner
sv: number of secondary vaginal sex partners
sa: number of secondary anal sex partners
sj: number of secondary injection partners

A represents HIV risk from a primary male partner; B is HIV risk from a secondary sex partner; C is HIV risk from a secondary injection partner.
Based on self-reported HIV status of male partner: self-reported HIV positive = 1.0; self-reported HIV negative/unaware and IDU = 0.15; self-reported HIV negative/unaware and non-IDU = .05.
Based on unpublished data on HIV prevalence among IDU and non-IDU men in Harlem and South Bronx, NY, USA.