Most patients in the COHERE group were either gay and bisexual men (about 60%) or heterosexual (30%): only 2.7% were injecting drug users. Ethnicity was not recorded in 42% of patients, was white in 41% and black in 12%. Their average age was 39 when they started ART, with an average baseline CD4 count of 218 cells/mm3 and a viral load of 70,500 copies/ml.
Different types of patients had different rates of viral failure and discontinuation. Heterosexual women, heterosexual men and male injecting drug users were 19%, 32% and 53% more likely, respectively, to experience viral load rebound than gay and bisexual men. People of black ethnicity were 33% more likely than white people to experience treatment failure.
High baseline viral load was associated with more failure after initial suppression: compared with patients with a baseline viral load of 20,000 to 100,000 copies/ml, people with baseline viral loads over 100,000 copies/ml were 28% more likely to rebound and those with baseline viral loads over 500,000 copies/ml were 53% more likely to rebound.
People who started in later years were more likely to maintain viral suppression. Compared with people who started in 2009-2010, people starting in 2002-2004 were 64% more likely to experience viral failure, and people who started in 2013-2014 14% less so.
A few groups had notably higher rates of complete ART discontinuation. Injecting drug users of either sex were over three times more likely to discontinue than others; people of black ethnicity 54% more likely than white; and young people under 25 years 90% more likely than people aged 35-45.