- Category: HIV Treatment
- Published on Tuesday, 28 February 2017 00:00
- Written by Gus Cairns
A study by the Centers for Disease Control and Prevention (CDC) presented at the recent Conference on Retroviruses and Opportunistic Infections in Seattle found that the proportion of time people with HIV in the U.S. spend in care but not virally suppressed has fallen from 40% to 10% in the last 15 years. The study also found that young people, black people, and people with public rather than private health coverage spent less time with viral load below 1500 copies/mL, the World Health Organization (WHO) threshold for HIV transmission.
The biggest problem the U.S. faces in reaching the UNAIDS 90-90-90 targets and having 72.9% of its entire HIV-positive population virally suppressed is the high proportion who have been diagnosed with HIV but are not in care. It is estimated that 61% of HIV transmissions in the U.S. come from people in this situation. Some transmissions, however, still come from people who are in care but are not virally suppressed (the "third 90").
Kate Buchacz from the CDC and colleagues analyzed figures from the HIV Outpatient Study (HOPS) cohort, a prospective cohort of 5000 HIV-positive people in care at a varied selection of HIV clinics, mainly hospital-based, in 9 U.S. cities. HOPS has been established since 1993, but this study looked at viral suppression among HOPS participants from 2000 to 2014.
The definition of being "virally suppressed" was the proportion of time spent with a viral load below 1500 copies/mL, which is not the usual definition of "undetectable" (usually below 50 copies/mL), but is the one the WHO uses as the threshold for infectiousness, as very few transmissions have ever been seen from someone with a viral load below this level.
There were 5873 people in the study, with an average follow-up of 5.4 years, amounting to 37,794 person-years of observation altogether. On average 15 viral load tests were taken per person, with a median time of 3.6 months between tests.
During that time people spent 86% of their time on antiretroviral therapy (ART) and 14% off it. The amount of time people spent on ART but not virally suppressed was 13% over the whole time period. In addition, 4% of people were not on ART but spent some time with viral loads under 1500 copies/mL.
The amount of time people spent not virally suppressed during 1 year fell over time. In 2000, 36% of people’s time on ART was spent with viral loads below 1500 copies/mL, and this was as high as 40% in 2003. It then fell steadily to 10% in 2014.
However, this includes time people were not on ART: while people in HOPS spent 90% of their time on ART in 2000, this fell to 80% during 2003-2004, then rose steadily to 93% in 2014.
Not all the people off ART were treatment-naive: in 2003-2004 more than half of those spending time off ART (11% of participants) were treatment-experienced and taking breaks. By 2014, only 3% of patient time was spent having a treatment break. This may have coincided with the period of maximum concern about long-term toxicities: the SMART study, the first one to show that it was generally better to stay on ART than not, announced its results in 2006.
The proportion of time people spent not virally suppressed while on ART -- and therefore experiencing true treatment failure or yet to be suppressed -- was 31% in 2000, falling to 7% in 2014.
This varied somewhat by drug class. In 2000, 22% of patient-time on NNRTI-based regimens was spent with viral loads over 1500 copies/mL versus 32% of time on protease inhibitor regimens; these proportions had fallen to 4% and 11%, respectively, by 2014. This does not take into account the fact that people on protease inhibitor regimens are more likely to be on second-line therapy or have drug resistance. In 2014, 9% of patient-time of people on integrase inhibitors, which were unavailable in 2000, was spent with viral loads over 1500 copies/mL.
In multivariate analyses, certain groups of people were more or less likely to spend time not virally suppressed. Older people were less likely, with the amount of time virally suppressed rising by 9% for every 10 years older, and people below 35 on ART were 50% more likely to spend time with viral loads over 1500 copies/mL than people over 50.
People with public rather than private health coverage were 24% more likely to spend time with viral loads over 1500 copies/mL, and black people were 19% more likely than white people. Women were more likely than men to have periods with viral loads over 1500 copies/mL -- 31% versus 22%, or 26% in heterosexual men alone -- but this association lost significance after controlling for race and insurance status, i.e., women were less likely to spend time unsuppressed because they were black or had public insurance, not because they were women.
This study reinforces the findings from another presented at the conference, which showed that disparities in age, race, and insurance status continue to affect the success of antiretroviral treatment. As this study looked at people in care who were largely on treatment, it shows that access to treatment may not be the sole determinant of viral load. Adherence and drop-outs from treatment caused by insurance problems may also play a role to play, though HOPS did not directly measure adherence.
K Buchacz, M Mendoza, C Armon, et al. Time spent with HIV viral load >1500 copies/ml among patients in HIV care, 2000-2014. Conference on Retroviruses and Opportunistic Infections. Seattle, February 13-16, 2017.Abstract 32.