A single value of HIV viral suppression (viral load <200 copies/mL during the last 12 months) is insufficient to identify individuals whose status may change and enable them to transmit the infection, according to findings published online August 5 in the Annals of Internal Medicine.

Nicole Crepaz, PhD, behavioral scientist at the Centers for Disease Control and Prevention’s Division of HIV/AIDS Prevention, Atlanta, Georgia, and colleagues used data from the National HIV Surveillance System for 630,965 individuals with HIV. Patients were diagnosed through 2016 from 33 jurisdictions, with 4.2% of them diagnosed in 2013. Median time between diagnosis and the end of 2013 was 11 years, and viral load was measured a median of twice in 2014. CD4+ count was included, and patients were alive through 2014.

A previously published investigation of 265,264 patients from 17 jurisdictions assessed for viral load in 2012 found two thirds of patients had achieved durable viral suppression (<200 copies/mL on all tests), but the other third maintained a high viral load, underscoring the compelling need to keep people with HIV infection in treatment.

The current study identified the percentage of people with a final viral load in 2014 of fewer than 200 copies/mL (durable viral suppression), those with 200 or more copies/mL (viral suppression never achieved), and copy-year, which measures viremia in terms of exposure to HIV over time.

Copy-year is similar to pack-year used to investigate the effects of smoking. It accounts for variability in infection, such as “10,000 copy-years,” which may represent 1000 copies of HIV daily in a patient’s bloodstream for 10 years, 10,000 copies of the virus daily for 1 year, or any other combination. Viremia over time is calculated as the geometric mean.

Of the infected individuals in 2014, 57.3% had a suppressed viral load on the most recent test, 47.6% had durable viral suppression throughout the year, and 8.1% had never achieved viral suppression.

The 51,114 patients who never attained viral suppression in 2014 had, on average, 17,530 copy-years of viremia. Of these 51,114 individuals, 28,765 (56.3%) had taken two or more viral load tests in 2014, indicating they were under care, and had an average of 21,387 copy-years of viremia.

“Assessing durable viral suppression and never virally suppressed can better inform treatment response and potential for HIV transmission. Clinicians may benefit from close examination of a patient’s historical context of clinic attendance, missed visits, medication adherence, and viral load patterns such as instability and wide swings, to identify patients who may be at risk of not achieving or not maintaining durable viral suppression,” Dr Crepaz told Medscape Medical News.

The investigators considered sex, age, race/ethnicity, and transmission category. Women, African-Americans, younger people, and patients with HIV infection from causes other than male-to-male transmission were more likely to not demonstrate viral suppression on their most recent viral load test, or to attain durable viral suppression.

“We found viral suppression to be particularly low among African-American risk groups compared to other races/ethnicities. There are several possible explanations, such differences in access to and use of health care and challenges in adhering to medications due to structural barriers like transportation and homelessness. However, it’s not clear that these factors completely explain the disparities. Strategies for these subpopulations may need to be tailored to the population, and even to a geographic area, to improve HIV care outcomes,” Dr Crepaz said.

The researchers conclude that a lone measurement of viral load may overestimate the number of individuals achieving durable viral suppression. Dr Crepaz summed up, “Our findings show that some persons who seemed to have received regular care for HIV infection still had viral loads high enough to substantially increase transmission risk, pointing out the need for intensified efforts to ensure that effective care and treatment reach everyone who needs it.”

Author: Ricki Lewis

Source: http://www.medscape.com/viewarticle/883965