Assessment of HIV prevalence among MSM in Tokyo using self-collected dried blood spots delivered through the postal service

Abstract

Background: Men who have sex with men (MSM) are at high risk of HIV infection. However, there are only few data on HIV prevalence in MSM in Japan. The objective of this study was to explore the HIV prevalence in MSM at Shinjuku 2-chome, a well known gay quarter in Tokyo. Methods: MSM directly collected the dried blood spot (DBS) self-collection HIV test kit from a drop-in center in Shinjuku 2-chome between August 2015 and December 2016. The participants collected their own blood by finger-prick and anonymously posted the kit to the laboratory. The participants accessed the study website and checked the results of their tests using unique ID and password. DBS was soaked in phosphate buffered saline overnight and the eluted sample was examined by the fourth generation HIV Ag/Ab test of LUMIPULSE (FUJIREBIO INC.), and followed by HISCL (Sysmex Corp.) when the first assay was positive. The result was defined provisionally positive if both were positive. Results: A total of 1702 HIV test kits were distributed and 1403 DBS were returned (return rate: 82.4%). Since 20.2% of participants collected the test kit more than once, the estimated number of actual test kit users was 1120. Based on the results of the test kit, 34 cases were provisionally diagnosed with HIV. The estimated prevalence was 3.04% (95% confidence interval: 2.03-4.04). Of these 34, 24 (70.6%) were later confirmed to be HIV-positive in the hospital, while the remaining 10 were lost to follow-up. Among the participants, 34.5% received HIV test for the first time. Especially in those aged 20-29, 46.0% were first time HIV testers. Conclusions: The prevalence of HIV infection in the study population was 3.04%. The high collection suggested a demand for this type of testing in MSM. The test should be expanded further to difficult-to-reach or hidden populations.