Two-thirds of HIV-positive people in care in the United States had all undetectable viral loads in 2012-2013, according to a quarter-million person analysis by the Centers for Disease Control and Prevention (CDC). But the remaining one-third -- more often women, blacks, Hispanics and younger people -- had detectable viral loads that could pose a risk of HIV transmission.
CDC investigators who conducted this study proposed that an undetectable viral load is "the ultimate clinical biomarker" for health of the HIV-positive individual and for HIV transmission risk. The National HIV/AIDS Strategy aims at a U.S. viral suppression rate of at least 90% by 2020. The CDC conducted this study to get a better understanding of durable viral suppression -- all viral loads below 200 copies/mL -- over a two-year period.
The analysis focused on people 13 years old or older diagnosed with HIV before 2011 while living in Washington, D.C., or one of 16 states that report complete viral load and CD4 cell count results to the CDC's National HIV Surveillance System. All study participants had at least one viral load test in 2011 and at least two during the observation period, 2012-2013. All were alive at the end of 2013.
In this study group, the CDC calculated percentage with durable viral suppression (all 2012-2013 viral load measures below 200 copies/mL), viremia copy-years (a cumulative viral load measure
) and person-time above 200, 1500 and 10,000 copies/mL. The researchers used regression models to determine differences between demographic groups in the three viremia outcomes.
Of the 238,641 people in the study group, 147,521 (62%) had durable viral suppression and 91,120 (38%) did not. Geometric mean viremia copy-years were 345 (meaning, for example, an average viral load of 345 copies/mL for one year or an average 690 copies/mL for 0.5 year). Study participants averaged 173 days in 2012-2013 with a viral load above 200 copies/mL (23.7% of the time), 124 days above 1500 copies/mL (17% of the time) and 84 days above 10,000 copies/mL (11.5% of the time).
Women had a 14% lower chance of durable viral suppression than men (univariate prevalence ratio 0.86, 95% confidence interval [CI] 0.85 to 0.86). Compared with whites, blacks had a 22% lower chance of durable suppression (multivariate prevalence ratio [mPR] 0.78, 95% CI 0.78 to 0.79) and Hispanics had a 10% lower chance (mPR 0.90, 95% CI 0.89 to 0.90). Men who have sex with men (MSM) had an independently higher chance of durable viral suppression than all other HIV transmission groups. Compared with people 55 years old or older, all younger age groups had lower chances of viral suppression, for example, mPR 0.74 (95% CI 0.73 to 0.74) for 25- to 34-year-olds and mPR 0.84 (95% CI 0.84 to 0.85) for 35- to 44-year-olds. People with inconsistent HIV care (more than a 12-month gap in viral load tests) had an 8% lower chance of viral suppression than people with consistent care (mPR 0.92, 95% CI 0.91 to 0.93).
These same demographic groups (women, racial minorities, non-MSM transmission groups, younger people, people with a gap in HIV care) had significantly higher viremia copy-years and spent significantly more time above 200, 1500, or 10,000 copies/mL than the reference groups.
Among the 91,120 cohort members who did not achieve durable viral suppression, geometric mean viremia copy-years stood at 7261 -- 21 times higher than the overall mean of 345 copy-years. People in this group averaged 438 days in 2012-2013 (60% of the time) with a viral load above 200 copies/mL, 316 days (43.2%) above 1500 copies/mL and 215 days (29.5%) above 10,000 copies/mL. Three groups averaged viremia copy-years above 10,000 copies: people 13 to 24 years old, people 25 to 34 years old and people with gaps in HIV care.
The CDC team stressed that the mean 7261 viremia copy-years in the 38% of the cohort without durable viral suppression indicate that their detectable viral load measures "were not simply blips." This large group -- more than one-third of the study population -- spent almost 30% of 2012-2013 with a viral load above 10,000 copies/mL and thus posed a meaningful HIV transmission threat while jeopardizing their own health.
The investigators called for more intervention "to improve retention in care and medication adherence so that more persons in HIV care achieve durable viral suppression." To identify people at risk of unsustained viral suppression, they suggested that providers closely examine each patient's clinic attendance, missed visits and viral load patterns. Even brief counseling by a provider, they added, can reduce HIV transmission risk behaviors.
Mark Mascolini writes about HIV infection.
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