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Time spent by people in HIV care in US with a transmissible viral load has fallen by three-quarters since 2000
Gus Cairns, 2017-02-18 23:50:00
A study by the US Centers for Disease Control and Prevention (CDC) presented at the
recent Conference on Retroviruses and Opportunistic
Infections (CROI 2017) in Seattle found that the proportion of time people with
HIV spend in care but not virally suppressed has fallen from 40% to 10% in the
last 15 years.
It also found that young people, black people and people with public rather
than private health insurance spent less time virally suppressed.
The biggest problem the United States faces in reaching the UNAIDS 90-90-90
target and having 72.9% of its entire HIV-positive population virally
suppressed is the high proportion in that country who are diagnosed but not in
care. It is estimated that 61% of HIV transmissions in the US 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’).
The CDC’s Kate Buchacz analysed figures from the HOPS cohort, an open,
prospective cohort of 5000 HIV-positive people in care at a varied selection of
HIV clinics, mainly hospital-based, in nine US cities. HOPS has been
established since 1993 but this study looked at viral suppression in HOPS
patients 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 used by the
World Health Organization as the threshold for infectiousness, as very
few transmissions have ever been seen from someone with a viral load below this
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
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 that whole
time period. In addition there were 4% of people who 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 one year fell
over time. In 2000 36% of people’s time on ART was spent with viral loads
below 1500 copies/ml and 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% in 2003 to 2004, then
rose steadily to 93% in 2014. Not all the people off ART were drug-naïve: in
2003-2004 more than half of those not spending time off ART (11% of people)
were treatment-experienced and taking breaks. By 2014, only 3% of patient time
was spent having a break off treatment. 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 be on ART than not, announced
its results in 2006.
The proportion of time people spent not virally suppressed while on ART and therefore in 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 (PI) regimens: this proportion of patient-time had fallen to
4% and 11% respectively by 2014. This does not take account of the fact that
people on PI regimens are more likely to be on second-line therapy and/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 ten years older, and people
aged 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 insurance were 24% more likely to spend time with viral loads over 1500
copies/ml, and black people 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 was of 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 have a role
to play, though HOPS did not directly measure adherence.