MedicalResearch.com Interview with: Qian An, PhD Epidemiologist/statistician Division of HIV/AIDS Prevention CDC MedicalResearch.com: What is the background for this study? Response: Since 2006, the Centers for Disease Control and Prevention (CDC) has recommended HIV testing for all persons aged 13-64 years old. Persons at high risk for HIV infection should be tested more frequently. Among sexually active men who have sex with men (MSM), repeat testing is recommended at least annually. An analysis in 2011 suggested that MSM might benefit from more frequent than annual testing.(1) Among non-MSM, repeat testing is recommended at least annually for persons at high risk, including persons who inject drugs (PWID) and their sex partners, those who have sex in exchange for money or drugs, heterosexuals who have had more than one sex partner since their most recent HIV test, and those whose partners are living with HIV.. Using statistical models based on renewal theory, we estimate the mean HIV inter-test interval (ITI) — meaning the average time period (in months) between two successive HIV tests — to describe temporal trends in HIV testing frequency among MSM, PWID and high-risk heterosexuals (HRH) and differences in testing frequency by age and race/ethnicity. A decrease in ITI means individuals are testing more frequently. (more…)