One test is enough: Japan's two-test rule for HIV treatment subsidies delays antiretroviral therapy without changing eligibility

Introduction: Japan achieves high retention and viral suppression among people on antiretroviral therapy, yet treatment starts late. Most people obtain subsidised treatment through a physical disability certificate for HIV-related immune dysfunction, which requires two blood tests at least four weeks apart. We quantified the diagnosis-to-treatment cascade, identified who waits and tested whether the second test changes certification. Methods: Retrospective cohort of people newly diagnosed with HIV at 11 designated AIDS core hospitals in 2015 to 2024. We measured intervals from screening to hospital visit and to antiretroviral therapy, and emulated certification from the first test alone and from the two-test rule under every possible number of non-laboratory criteria (k = 0 to 8). Results: Of 1302 people (96% men; 68% with CD4 <350 cells/L or AIDS), 1036 (80%) followed the two-test pathway and 261 started treatment after one test, mostly because of AIDS or acute infection. People reached the hospital a median of 11 days after screening. Treatment then began a median of 70 days after the first visit in the two-test pathway and 11 days in the single-test pathway; 0.2% and 60.9% started within 14 days. Delay rose with CD4 count: 46 days when the mean count was [&le;]200 cells/L, 117 days when it was >500 with a laboratory criterion (16% of the two-test pathway) and 334 days when it was >500 without one (3%; adjusted hazard ratio 0.14, 95% confidence interval 0.09 to 0.23). Medians ranged from 35 to 96 days across facilities. The second test changed little: the first CD4 count agreed with the mean of two (intraclass correlation coefficient 0.959), HIV-RNA [&ge;]5000 copies/mL persisted in 97.6%, and certification status agreed in 99.0% for k [&ge;]1 (92.5% for k = 0), with discordance concentrated near 500 cells/L; the first test gave a milder grade in at most 2.9%. Conclusions: The statutory second test adds at least four weeks before antiretroviral therapy in Japan without changing who is certified, and delays most the people with the highest CD4 counts. Certification on a single test, with treatment separated from the subsidy procedure, would remove a delay that has no clinical or administrative justification.