Pre-exposure prophylaxis (PrEP) is currently used as a measure that in preventing HIV transmission during unprotected sex. Though not foolproof, studies have shown taking daily doses of tenofovir the drug reduces the risk by 92% in preventing HIV infection.

Since 2012, CDC has recommended PrEP for homosexual, bisexual men and for men who were in relationship with HIV-positive partners. However, UCLA Fielding School of Public Health suggested changes in the recommendations provided by CDC, primarily filling the existing gaps in guidelines drafted by CDC.

The UCLA research group suggested changes in the federal guidelines established by CDC after carrying out an extensive study in collaboration with Los Angeles LGBT Center. The researchers feel the guidelines established by CDC omit important characteristics related to sexual behavior, and therefore someone might be at higher risk of infection. Also, the group developed an online risk assessment calculator based on their findings that could fill the gap in recommendations.

The co-author of the study and a professor of biostatistics, Robert Weis said, β€œTo the best of our knowledge, this PrEP Calculator is the first of its kind to be based on real-world data.” He also said the calculator helps the users with the risk assessment to make informed decisions.

The study was carried out with the help of The Los Angeles LGBT Center which is one of the largest HIV testing providers in Los Angeles County for LGBT community. The center serves nearly 13K people in a year. The UCLA team collected data on behavioral risk factors for HIV among clients at each visit and what characteristics distinguished men who have sex with men, who were HIV-negative throughout testing and from people who subsequently tested positive for HIV.

Using this data on behavior amounting to sex only, the researchers built an HIV-risk algorithm, a mechanism for recommending PrEP to clients in the center. The data collected for the study included questions on the subject of substance use, the number of sex partners, age, partner level data and race or ethnicity.

The researchers also noted that when individuals with a risk score of greater than 5 was asked to use the calculator, 75% of HIV infections were averted assessed through follow-up testing. The calculator aided in the effective use of PrEP.