Currently, the most effective method to reduce further transmission and optimize the well-being of those with HIV is to achieve and maintain viral suppression. The HIV Care Continuum is commonly used as a framework to monitor progress towards this end goal. As such, it is important to understand the dynamics of progressing through each stage of the continuum in order to implement effective targeted interventions.

This study was, to the best of our knowledge, the first to evaluate a cohort of HIV-positive individuals through the entire course of the HIV care continuum: from diagnosis through viral suppression. Thus, factors associated with overall viral suppression and progression to each intermediate continuum stage could be evaluated within the same population, allowing for a more standardized comparison of the relevant determinants between the stages. This type of comparison was lacking in the current literature, in which information about the continuum stages must be derived from different studies based on different study populations.

As such, our study (Chapter 2) was able to evaluate associations at each continuum stage and provide insight into the consistency of these associations throughout the continuum. We observed that certain factors associated with overall viral suppression were not always significant at every stage. Conversely, some factors that were associated with a certain intermediate stage were not associated with overall viral suppression. For example, race/ethnicity was significantly associated with viral suppression among everyone diagnosed. However, there was no difference between the ethnic groups with regards to linkage and retention. Therefore, within this population, interventions and policies aimed towards increasing linkage/retention in these ethnic groups in hopes of improving viral suppression rate would be misdirected and ineffectual. Our results demonstrate the importance of understanding the continuum as a whole in any given population to best direct public health resources.

Another aspect relevant to the appropriateness of the HIV care continuum is the designated definitions of the intermediate stages. The intermediate stage with the most variation in definition is retention in care. For any given population, any retention measure used must be significantly associated with increased viral suppression (among the retained). However, another perhaps more clinically practical perspective in deciding the most appropriate retention measure definition would be determining the measure that best predicts viral suppression. This study (Chapter 3) was also the first to evaluate eight different measures of retention, with measures involving kept visits, missed visits, and HIV laboratory tests, among a single population. Further, our study was among the few to apply a non-traditional statistical-learning method (k-folds cross validation) to estimate the accuracy of the retention measures in predicting viral suppression among new patients. The results demonstrated that although no gold standard retention measure may exist, each retention measure evaluated was significantly associated with increased viral suppression as well as positive predictor of viral suppression. However, the difference between the ranking of strength of association (odd ratio) and predictive accuracy (from cross-validation) indicates that traditional statistical methods alone may not best determine prognostic ability of the measures. Methods such as those in statistical learning can be utilized in evaluating the most appropriate measure for each population.

Aside from viral suppression, another goal of HIV counseling and care is to reduce the sexual behaviors that promote transmission. The literature is mixed with regards to the direction of change in high-risk sexual behaviors at different points after HIV diagnosis: 1) following linkage to care; and 2) following initial viral suppression. Our analyses (Chapter 4) also evaluated the direction of any change in sexual behavior at these two time points using STD incidence as a proxy. The results provided more support for an attenuation in high-risk behavior possibly related to treatment adherence than for an increase due to “HAART complacency”. In addition, the findings were more consistent with a reduction in high-risk behaviors observed following HIV diagnosis. Ethnicity was also associated with reduction in STD incidence. Further sub-analysis based on the association with ethnicity revealed a subgroup of clients that were at potentially high-risk for HIV transmission (no reduction in high-risk sexual behavior, concurrent STD infection, and less likely to be virally suppressed). Future studies and programs should focus on identifying these high-risk subgroups in addition to the broader analyses on sexual behavior change.