Title: Examining HIV Viral Load and Longitudinal Assessments of Viral Suppression of Individuals Living with HIV in Washington, District of Columbia
Description: To end the HIV epidemic, prevention of new HIV infections will be contingent on preventing at-risk individuals from acquiring HIV and supporting people living with HIV in achieving and sustaining viral suppression throughout their lifetime. The underlying motivation for this dissertation is the recent evidence that new HIV infections can be prevented when people living with HIV achieve and maintain viral suppression. In response, three studies were conducted. The goal of this dissertation was to advance our understanding of HIV viral suppression patterns over time among clinically engaged adults living with HIV and examine current limitations in viral suppression monitoring. First, a systematic review evaluated the existing literature for evidence of longitudinal assessments of viral suppression among people living with HIV. Among 896 publications identified during the database search, 50 publications met the study criteria and were included in the review. Among these studies, 78% were implemented in the United States, 72% assessed viral suppression using viral load results abstracted from clinical medical records, and 22% used surveillance data from HIV-laboratory based reporting.

Five distinct longitudinal measurement methods were identified, including (a) estimates requiring more than one viral load within an observation period to be below a suppression threshold; (b) estimates comparing the first and last viral load during an observation period; (c) reporting multiple proportions of participants maintaining viral suppression across an observation period; (d) estimating viremia copy-years and estimating person-time above a suppression threshold, and; (e) other methodology to assess longitudinal viral suppression such as data weighting and group-based trajectory modeling. Half of the studies reported the proportion of individuals with all viral loads below a certain threshold (e.g., ≤200 copies/mL). Most studies (70.0%; 35/50) were published in the last five years (2015 – 2019) and describe viral load data collected between 2013 and 2018, highlighting recent efforts by researchers to describe viral suppression using longitudinal approaches. Next, data from a longitudinal electronic medical record-based prospective cohort study of people living with HIV seeking care in Washington, District of Columbia, were used to describe longitudinal changes in viral suppression and assess the relationship between prior virologic history and virologic failure events during follow-up.

Among 3556 participants, 29% did not maintain viral suppression during a five-year period, and instances of viral suppression status fluctuations were observed. Participants with a history of fluctuating viral suppression were found to have a higher rate (RR=2.40; 95% CI: 2.03 – 2.84; P<0.01) of virologic failure events during follow-up, compared to participants with sustained viral suppression before the observation period. Lastly, a third study used the same data source to assess differences between viral suppression estimates derived from different measurement methods and evaluate the impact of data triangulation on longitudinal viral suppression measures. Among 3452 participants (median age 48; 73% cisgender males; 77% non-Hispanic black), 69% had all viral load results suppressed (<200 copies/mL) during a four-year observation period, 28% had both suppressed and unsuppressed viral loads, and 2% had all viral loads unsuppressed. Compared to cross-sectional viral suppression measurement methods, longitudinal measurement methods resulted in lower proportions of virally suppressed participants.

Data triangulation added 2293 viral load data points and resulted in lower viral suppression estimates. These findings highlight the need to reconsider current viral suppression measurement methods to improve the accuracy of estimates reported in surveillance reports and epidemiologic studies. Overall, this dissertation addresses important questions related to viral suppression by describing the frequency of viral suppression status fluctuations that occur throughout an extended observation period, quantifying the occurrence of repeated virologic failure events, and comparing several measurement techniques to assess appropriate methods to describe viral suppression over time. Recently, the United States Department of Health and Human Services, together with the White House, set forth the “Ending the HIV Epidemic: A Plan for America” initiative, with a goal to end the HIV epidemic in the United States within the next ten years. To reach this goal, the initiative calls for a 75% reduction in new HIV infections by 2025 and a 90% reduction by 2030.

Treating people living with HIV rapidly and effectively with ART is an important strategy to carry out these efforts. This dissertation demonstrates that assessing the ability of people living with HIV to maintain viral suppression over time is also critical.