U.S. HIV Group Spends 25% of Time With High Viral Load
More than 14,500 people in care in six U.S. clinics spent one quarter of their time with a viral load above 1500 copies.1 A viral load that high raises chances of passing HIV to a sex partner and threatens the HIV-positive person's health. Study groups that spent more than one quarter of their time in care with a viral load above 1500 copies included blacks (26% of time), people 16 to 39 years old (32% of time), and people not taking antiretroviral therapy (58% of time).
HIV-positive people with an undetectable viral load -- below 40 or 50 copies per milliliter of blood -- rarely if ever pass HIV to a sex partner. Research shows that the risk of sexual HIV transmission rises when the viral load stands above 1500 copies.2-4 People with a viral load above 1500 copies usually have not started antiretroviral therapy, started treatment and missed a few doses or stopped entirely, or started an antiretroviral combination that's now failing.
Understanding how often the viral load of HIV-positive people in care stands above 1500 copies can give health authorities a better idea of how many positive people run a risk of passing HIV to their sex partner. Learning which groups of people are more likely to have a viral load above 1500 copies can help health officials and HIV providers work harder to get those people into care and onto steady, effective antiretroviral therapy.
For those reasons, researchers from the Centers for Disease Control and Prevention (CDC) and colleagues at the six U.S. clinics conducted this study to determine how much time HIV-positive people in care spend with a viral load above 1500 copies and how often viral loads are above that level in different HIV groups.
How the Study Worked
The study involved HIV-positive adults in care in at six clinics in six U.S. cities between April 2009 and March 2013. Everyone had at least two viral load tests during that time, with at least 30 days between the first test and the last test. The researchers called this group the observational cohort. Additional analyses to assess time with a viral load above 1500 copies according to antiretroviral therapy use involved a separate set of HIV-positive people enrolled in a clinical trial at the same six clinics. The researchers called these people the trial participants.
Total observation time for each person started with that person's first viral load test and ended with the last viral load test. The researchers calculated the percentage of time with a viral load above 1500 copies by determining the viral load between each pair of tests, in this manner:
- All days between two 1500-plus results were above-1500 days.
- All days between two sub-1500 results were sub-1500 days.
- If the viral load stood above 1500 copies on one test and below 1500 copies on the next, or the other way around, the researchers calculated days spent with a viral load above 1500 copies by a formula incorporating initial viral load, next viral load, and days between viral load measurements.
Next the CDC team divided observational cohort patients into several groups according to (1) percentage of viral load pairs with more than 6 months between the first and second, (2) years of entry into the analysis (2009-2010, 2010-2011, 2011-2012), (3) whether the first viral load was above 1500 copies, (4) age, (5) race/ethnicity, (6) sexual orientation, (7) injection drug use as an HIV exposure factor, (8) health insurance status, and (9) clinic site. For the trial participants, the researchers divided patients into groups according to (1) antiretroviral therapy status at entry to the study, (2) study group in the trial these people were participating in, (3) new or established patient, and (4) clinic site.
Finally, the research team used standard statistical methods to compare these groups according to time with a viral load above 1500 copies.
What the Study Found
The main study group (the observational cohort) included 14,532 HIV-positive people with two or more viral load measurements. About one third of this group was gay or bisexual men, another third heterosexual men, and another third women. Only 13% of study participants had injection drug use as a risk factor for becoming infected with HIV.
About one third of the group was 16 to 39 years old, one third 40 to 49, and one third 50 to 85. While 64% of study participants were black, 18% were Hispanic, and 17% white. More than 90% of these people had prescriptions for antiretroviral therapy during the 3 years from 2010 through 2012. About 15% of study participants had private insurance, 15% used Medicare, 25% used Medicaid, and the rest relied on Ryan White funding or charity. (Ryan White funding supports care for low-income, uninsured, and underinsured people with HIV and their families.)
Median observation time for the group (time between first and last viral load result) was 1073 days (almost 3 years), and study participants had a median of 9 viral load measures. Viral loads stood above 1500 copies an average 23% of the time per person, or 84 days per year per person.
Percentage of observation time with a viral load above 1500 copies varied a good deal across the different subgroups analyzed: Groups with the most time spent above the 1500-copy mark were those whose first viral load stood above 1500 copies (Figure 1), people for whom more than 25% of consecutive viral loads were measured more than 6 months apart (Figure 1), people whose CD4 count lay below 350 when their viral load was first measured (Figure 1), people 16 to 39 years old versus older (Figure 2), blacks versus whites (Figure 2), women and heterosexual men versus gay men (Figure 2), people who injected drugs (Figure 3), and people who did not have private insurance (Figure 3).
Statistical analysis that accounts for several viral load risk factors at the same time linked being in some of these groups with a longer time above 1500 copies, regardless of whatever other risk factors someone had. The analysis expresses differences between groups as an adjusted rate ratio (aRR). An aRR above 1.0 indicates longer time with a viral load above 1500 when comparing one group with another, and an aRR below 1.0 indicates shorter time with a viral load above 1500. For example, a rate ratio of 1.38 (16- to 39-year-olds versus 40- to 49-year-olds in the list below) means the younger groups spent 38% more time with a viral load above 1500 copies than the older group, regardless of other factors that might affect viral load.
- First measured viral load above 1500 versus below 1500: aRR 4.03
- More than 25% of viral load pairs measured more than 6 months apart versus 10% to 25% of viral load pairs measured more than 6 months apart: aRR 2.04
- More than 25% of viral load pairs measured more than 6 months apart versus fewer than 10% of viral load pairs measured more than 6 months apart: aRR 1.52
- CD4 count below 350 versus above 350 at first viral load measure: aRR 1.15
- 16 to 39 years old versus 50 to 85 years old: aRR 1.38
- 40 to 49 years old versus 50 to 85 years old: aRR 1.18
- Black versus white: aRR 1.24
- Gay/bisexual men versus heterosexual men: aRR 0.94 (6% less time spent above 1500 by gays)
- Injection drug use versus no injection drug use: aRR 1.21
- Ryan White/charity support versus private insurance: aRR 1.33
- Medicaid versus private insurance: aRR 1.40
- Medicare versus private insurance: aRR 1.29
The study included 1779 trial participants in the additional analysis of how antiretroviral use affected time spent with a viral load above 1500 copies. Trial participants were similar to the larger observational group (discussed just above) in age, sexual orientation, CD4 count, and most other factors except for race: 72% of trial participants were black, compared with 64% of the observational cohort. The median observation period in trial participants measured 1032 days, and these people had a median of 11 viral load measures.
Among all trial participants, viral load exceeded 1500 copies 26% of the time per person, or 95 days per year per person. This rate is similar to the 23% seen with the observational cohort (above). People not taking antiretroviral therapy when they entered the study period or in the next 12 months spent 58% of their time with a viral load above 1500 copies. In contrast, people who started antiretroviral therapy in the first 12 months of observation time spent 45% of their time with a viral load above 1500. And people already taking antiretrovirals when they entered the study spent 21% of their time with a viral load topping 1500. People who had just begun care at one of the six clinics spent 34% of their time with a viral load exceeding 1500 copies.
What the Results Mean for You
This large study of HIV-positive people in care in the United States found that they spent about 25% of the time with a viral load above 1500 copies -- even though 90% took antiretroviral therapy at some point. A viral load above 1500 copies signals a higher chance of passing HIV to a sex partner and so contributing to the almost 50,000 new HIV infections seen yearly in the United States. Time spent with a viral load above 1500 copies was even greater -- 58% -- in people not taking antiretroviral therapy.
Only about 10% of this study group did not take antiretroviral therapy during the study period. That low percentage reflects advice from U.S. HIV treatment experts, who recommend that everyone with HIV infection start therapy regardless of their CD4 count or viral load.5 Antiretroviral combinations available today are stronger, safer, and easier to take than combinations available 10 or 15 years ago. If everyone in this study group took antiretrovirals and didn't miss many doses, the average time spent with a viral load topping 1500 copies would be lower -- and so the group's overall risk of spreading HIV infection would be lower.
Besides this community-wide benefit of having a viral load below 1500, having a lower load (and higher CD4 count) cuts chances that the individual patient will get AIDS diseases and some non-AIDS diseases. The antiretroviral treatment goal for anyone taking antiretroviral therapy should be a viral load below 40 or 50 copies. A load that low means HIV has stopped multiplying in the body, although HIV remains in resting T cells and will become active again if antiretroviral therapy stops.
The study also identified several groups that spent more time with a viral load over 1500 than comparison groups:
- People not taking antiretrovirals (almost everyone not on treatment will have a detectable viral load, and often a high viral load)
- People who go a longer time between viral load measures (possibly because they are missing clinic appointments)
- People younger than 40 (a group that sometimes fails to take antiretroviral drugs regularly)
- Blacks (perhaps because of poor access to health care)
- People without private health insurance (who are poorer and so may have poor access to health care and more overall health problems than wealthier people)
Despite possible social and economic disadvantages, people in these groups should find the motivation to get care for their HIV infection, stay in care, start antiretroviral therapy, and take antiretrovirals on time, as their provider instructs. HIV providers can connect patients with a case manager, who will help with problems involving insurance, transportation, and child care. People who follow those steps are now living almost as long -- or as long as -- people without HIV infection. At the same time they're cutting the chance of passing HIV to sex partners.
A final note: having a low or undetectable viral load does not eliminate the chance of passing HIV to sex partners. Everyone with HIV should use condoms during sex -- to prevent transmission of HIV as well as other dangerous sexually transmitted infections. Condoms also protect the HIV-positive partner from picking up dangerous sexually transmitted diseases.
- Marks G, Gardner LI, Rose CE, et al. Time above 1500 copies: a viral load measure for assessing transmission risk of HIV-positive patients in care. AIDS. 2015;29:947-954.
- Attia S, Egger M, Muller M, Zwahlen M, Low N. Sexual transmission of HIV according to viral load and antiretroviral therapy: systematic review and meta-analysis. AIDS. 2009;23:1397-1404.
- Quinn TC, Wawer MJ, Sewankambo N, et al. Viral load and heterosexual transmission of human immunodeficiency virus type 1. N Engl J Med. 2000;342:921-929.
- Tovanabutra S, Robison V, Wongtrakul J, et al. Male viral load and heterosexual transmission of HIV-1 subtype E in northern Thailand. J Acquir Immune Defic Syndr. 2002;29:275-283.
- HHS Panel on Antiretroviral Guidelines for Adults and Adolescents. Guidelines for the use of antiretroviral agents in HIV-1-infected adults and adolescents. Last updated April 8, 2015.