Study suggests improvements to HIV care cascade measurements

September 15, 2015

The HIV care cascade is a commonly used framework that estimates the number of HIV-infected individuals in a geographic area according to their HIV diagnosis, care and treatment status.

The cascade, also commonly called a continuum, is used with surveillance data collected by state and city health departments in the United States to estimate the proportion of HIV-infected persons who have been diagnosed, have ever sought HIV care, are currently in care and/or are virally suppressed.

Dr. Kimberly Powers

Kimberly Powers, PhD, assistant professor of epidemiology at the UNC Gillings School of Global Public Health, is senior author of a newly published study that reviews challenges and biases that may limit the accuracy and usefulness of the HIV care cascade as it is currently implemented. Catherine Lesko, PhD, recent graduate of the Department of Epidemiology at the Gillings School, is first author of the paper.

Lesko and co-authors interviewed public health practitioners and epidemiologists responsible for HIV surveillance at the North Carolina Division of Public Health to gain a better understanding of local continuum estimation practices. The research team also reviewed programmatic guidance and HIV estimates from other jurisdictions in order to gain use comparisons. Finally, they analyzed surveillance data from the N.C. Division of Public Health to illustrate the existence and magnitude of potential biases.

“The HIV care cascade has become a canonical framework for describing the state of HIV care and treatment in many populations worldwide, but there are several issues with the ways in which cascade estimates are being derived,” Dr. Powers explained. “As noted in the paper, some of the main threats to accuracy include fragmentation of data across different sources, the use of laboratory reports as proxies for HIV care visits and challenges in distinguishing HIV care disengagement from migration out of a jurisdiction. Each of these issues makes it difficult to know the true state of the HIV epidemic in a given population.”

The team concluded that the estimation abilities of the HIV care cascade could be improved by triangulating data sources within and across jurisdictions and by conducting sensitivity analyses. They also recommend quantifying the uncertainty present in surveillance estimates rather than offering artificially precise numerical estimates. Further, they advise that all published estimates should include a detailed description of data collection procedures.

The HIV care cascade is a critical tool for conceptualizing and monitoring the HIV epidemic in the U.S. and globally. However, challenges to its accurate implementation are often afforded insufficient attention. Given the importance of the continuum in monitoring and evaluating initiatives to control the epidemic and improve the lives of HIV-infected people, considerable effort should be devoted to improving the tool’s accuracy and utility.

The full article, titled “Measuring the HIV Care Continuum Using Public Health Surveillance Data in the United States,” was published online Aug. 6 by the Journal of Acquired Immune Deficiency Syndromes.