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The HIV care cascade: models, measures and moving forward

Publication year: 
Corporate author: 
MacCarthy S et al
Publication details: 
Santa Monica:Journal of the International AIDS Society, 2015

The advent of antiretroviral therapy (ART) was meant to change the course of the AIDS epidemic. In many ways it did: there was a dramatic reduction in AIDS-related morbidity and mortality, and in some contexts HIV/AIDS is now a
manageable chronic illness. Yet, in high- and low-income countries alike, studies continue to document delays in the utilization of available services, including HIV counselling and testing, treatment and continued engagement in care services. These delays are correlated with compromised treatment response and missed opportunities for preventing HIV transmission [1]. The HPTN 052 study published by Cohen and colleagues demonstrated a 96% reduction in the number of
linked HIV-1 transmissions due to early treatment initiation. These results further illustrate the importance of earlier ART initiation to achieve viral suppression, the mechanism highlighted by authors as largely responsible for decreased transmission rates. Notably, few HIV-positive individuals reach
viral suppression. In 2012, for example, the US Centers for Disease Control and Prevention (CDC) released data indicating that in the United States, only 25% of individuals living with HIV were sufficiently engaged in care to achieve viral
suppression [3]. As such, substantial evidence suggests that both access to services and the timing in which services are reached are critically important to improving individual and population health outcomes. But it remains unclear how best to measure the timing in which services are accessed, further complicating efforts to identify the factors associated with delayed presentation
to particular stages of the adult HIV care cascade (hereafter referred to as the cascade). Furthermore, recent reviews from both high-income and low-income contexts have highlighted definitional questions regarding the cascade
and underscore the need for greater clarity. A closer analysis of different models and associated measures of the cascade across settings remains lacking.