What Is the HIV Treatment Cascade?

And Why It Should Be of Concern to All of Us

Treatment Cascade
Image &copy# James Myhre

The HIV Treatment Cascade is a representational model used by federal, state and local agencies to better identify gaps in care delivery to people living with HIV. Also known as the HIV/AIDS Care Continuum, the model offers a compelling illustration of the proportion of Americans who are engaged at each step of HIV care in descending order from:

  1. The estimated number of individuals infected with HIV;
  2. The proportion that have been diagnosed;
  3. The proportion that have been linked to care;
  4. The proportion that are retained in care;
  5. The proportion that require antiretroviral therapy;
  6. The proportion that actually receives therapy, and;
  7. The proportion able to maintain undetectable viral loads (considered the measure of treatment success).

The model was first described by Dr. Edward Gardner and his colleagues at the Denver Health Department in March 2011. The analysis found that there was a significant drop off between each step of the continuum to the point where it created an inverted pyramid when placed in diagrammatic context ( see illustration).

At its most dismaying, what the HIV Treatment Cascade shows is that of the nearly 1.2 million Americans estimated to have HIV, only about 25% have been able to successfully navigate the care continuum from diagnosis to treatment to the complete suppression of HIV viral activity.

Worse yet, of the 66% who are initially linked to care, nearly half of those (approximately 219,000 people) are either lost to follow up or unable to access HIV-specific care.

While there have been advances in patient diagnoses and linkage to care from 2010 to 2012 (increasing 2% and 4%, respectively), losses of between 3% and 4% were noted in all other categories.

What the HIV Treatment Cascade Tells Us

These figures underscore the challenges ahead for policymakers as current U.S. guidelines call for not only universal HIV testing of all Americans age 15-65 but also calls for initiation of HIV therapy at the time of diagnosis irrespective of CD4 count.

Ultimately, the aim of these policies is to effectively treat as many people as possible to bring down the so-called "community viral load" (CVL) within high prevalence populations. By doing so, the spread of HIV could be dramatically decreased as infectivity of that population gradually lowered.

However, it begs to question as to whether these goals can be realistically achieved given the significant gaps in the care continuum, particularly among African Americans who are less likely to be linked to care (62%) and less likely achieve viral suppression (21%).

Younger Americans (ages 25-34) fare even worse, with only 56% linked to care and only 15% achieving undetectable viral loads.

Additionally, some have argued that, as a tool, CVL is a flawed indicator for infectiousness insofar as it underplays the impact of individuals with high viral loads while underestimating the viral loads of those who remain undiagnosed. One such study conducted by the University of Chapel Hill, North Carolina suggests that the CVL may, in fact, be twice that currently reported when epidemiological adjustments are made.

Closing the Gaps

In order to narrow some of the gaps in the care continuum, enhanced care delivery systems are being explored by a number of state and municipal health authorities. Among the key aims:

  • Provide greater access to HIV-specific care, particularly for marginalized communities. Increased access to Medicaid and private health insurance under the Affordable Care Act may help alleviate the health disparities in affected populations.
  • Streamline intake by testing, linking to care, and treating patients in an integrated facility (a system popularly known as TCL-Plus). San Francisco, Los Angeles, Birmingham, and Washington, D.C. are among the U.S. cities regularly cited as exhibiting the best TLC-Plus practices.
  • Intensify efforts to locate "lost" patients and re-link them to care. In 2013, the New York City Department of Health and Mental Hygiene managed to find 689 of 797 HIV patients lost to follow-up, eventually reconnecting 77% of them to appropriate medical care.
  • Share electronic medical records between authorized health agencies to ensure "electronic outreach" to those who are either lost to follow-up or in need of treatment. Between 2009 and 2011, the Louisiana Department of Health was able to identify and alert 345 HIV-positive patients through their Louisiana Public Health Information Exchange (LaPHIE), a real-time, bi-directional electronic health database.  
  • Explore both novel and traditional means to improve adherence among people on antiretroviral therapy. This includes increasing doctor-patient interactions. Studies suggest that patients with one doctor visit per year are 94% more likely to become ill or die than someone with four. Increased doctor-patient interaction also correlates to improved drug adherence rates.
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