MSM cohorts. Most seropositive DU (n = 69 [58%]) did not receive any early treatment, 28 (23%) received zidovudine monotherapy, and 23 (19%) received other ineffective antiretroviral therapy before AIDS-diagnosis. The mean age of DU participants at the time of (imputed) seroconversion was 31.5 years (range 19.1–55.9 years). A DNA sample was available from all 120 DU participants, hence all were included in further analyses.
