Poor knowledge of sexually transmitted infections (STIs) and HIV among people with HIV (PLHIV) could worsen life quality. We aimed to investigate their STI and HIV knowledge, disclosure and undetectable = untransmittable (U=U). We proposed an anonymous questionnaire regarding STI and HIV to PLHIV attending ten Italian outpatient infectious diseases clinics. Moreover, disclosure and U=U were investigated. The calculated sample size was 178 people. Considering a missing response of 10%, the final sample size was 196. We enrolled 200 PLHIV (73.5% males), with a median age of 52.5 (IQR 41-59) years. The mean score was 7.61 ± 1.22 with no difference by gender, education, and employment. Significant statistical difference was observed by sexual orientation; bisexuals and those who preferred not to answer had a lower score than heterosexuals and MSM (p = 0.0032). PLHIV showed poor knowledge about HIV transmission (25% appropriately answered). Nearly 30% responded that virologically suppressed PLHIV could transmit the infection. Finally, 137 (68.5%) and 158 (79.0%) disclosed to the general practitioner and family and friends, respectively. Nearly 52.0% knew the meaning of U=U, and 83.6% highlighted its positive rebound. In conclusion, important knowledge gaps are present among PLHIV regarding U=U, and its implications are little-known. Improving PLHIVs' awareness will undermine self-stigma and enhance life quality.
Keywords: HIV; PLHIV; STI; U=U; disclosure; education; knowledge; people living with HIV; prevention; survey.