classification based on the proportion of condomless sex occasions is 100%, which would not distinguish him meaningfully from the man in Example 1.Example 3. A woman had sex with two male partners, steady HIV-negative and exchange HIV-unknown. The one sex occasion with the steady partner was condomless; with the exchange partner, she had seven sex occasions, of which one was condomless vaginal and three were condomless anal (total sex occasions = 8; condomless sex occasions = 5). Thus, RI 1 (Partner 1) = 0.01*(0.08*1) = 0.001; RI 2 (Partner 2) = 0.90*(0.01*1+1.38*3) = 3.74; RI Total = 0.001+3.74 = 3.74. The proportion of condomless sex occasions would be 62.5%. Relative to Example 1, the RI shows this person's risk approximating his, though the proportion of condomless occasions shows her to be at considerably less risk.Using our RI, possible misclassifications of risk based solely on the proportion of condomless sex occasions were identified. RI offers greater precision in estimating risk within psychiatric and potentially other populations now that Brazil is considering pre-exposure prophylaxis (PrEPPrEPBrasil.com.br) for those at high risk. Additional behavioral and infection rate data are needed to further differentiate and validate high risk.