Treatment Cascade Researchers Make Case for HIV Care as Secondary Prevention for Both Sexual and Drug Behavior

People living with HIV who are engaged in care are less likely to participate in risk behaviors like unprotected sex or using non-sterile injecting equipment, according to Edward Gardner, M.D., medical director of the Infectious Diseases Clinic, and director of clinical research, at Denver Public Health.

In 2011, Gardner and colleagues published a paper in Clinical Infectious Diseases that estimated how many individuals with HIV in the U.S. are engaged at distinct points in the continuum of care from diagnosis through viral suppression, showing a steep drop-off along the way. Originally referred to as the "Gardner cascade" or the "treatment cascade," the model gained broad use in HIV planning, public policy and program design as the "HIV care continuum."

Gardner mined a decade of research for a webinar for the National Center for Innovation in HIV Care (NCIHC), asserting that engagement across the HIV care continuum was associated with a reduction in HIV risk behaviors.

He cited a 2005 meta-analysis of 11 studies looking at self-reported risk behaviors before and after HIV diagnosis in which people who received a positive diagnosis were 53% less likely to have unprotected anal or vaginal intercourse than people who were unaware of their HIV status.

Further, he noted that a separate study observed a 50% reduction in unprotected sex among people living with HIV who were engaged in care, compared with individuals who had been diagnosed with HIV but were not engaged in care.

"What we're seeing here is a good reduction, both after diagnosis and after linkage to care, in HIV risk behavior and this will help to reduce transmission to others," Gardner said.

The same pattern was observed after initiation of antiretroviral therapy among positive people who injected drugs in a 2012 paper.

"Even though they already knew they had HIV, once they went onto therapy, risk behaviors decreased, including any injecting, sharing needles, any sex -- which was a little flatter -- but unprotected sex definitely was decreased over time," Gardner said.

According to the U.S. Centers for Disease Control and Prevention, in 2011 86% of people living with HIV are currently aware of their status, while only 40% are engaged in care, 37% are receiving antiretroviral therapy and 30% have achieved viral suppression.

While these numbers have improved over the past few years, Gardner emphasized continued effort was required to increase the proportion of people living with HIV who were effectively engaged in care.

He said randomized controlled trials and other studies had highlighted the importance of addressing stigma among priority populations, undertaking intensive outreach and helping clients navigate complicated health care systems, improving client messaging on the importance of engagement, investing in substance abuse counseling and treatment, improving mental health diagnosis and care, addressing housing and homelessness issues, decreasing competing needs (such as those relating to food and clothing) and improving health care delivery systems.

The NCIHC is currently holding a series of webinars for Ryan White-funded AIDS service organizations and community-based organizations. Further information is [[available on the center's website.

Katherine Moriarty is a consultant and freelance writer, based in Vancouver. She has 10 years of experience in the intersecting fields of public health and community development, with a focus on bloodborne virus policy and programming.