No Gold Standard for Measuring Patient Retention in HIV Care

Fran Lowry

June 05, 2012

June 5, 2012 (Miami Beach, Florida) — The commonly used ways of measuring patient retention in HIV medical care are equally effective in predicting viral load suppression, even though they measure retention slightly differently.

The results from a study of more than 10,000 patients at 6 academic HIV clinics were presented here at the 7th International Conference on HIV Treatment and Prevention Adherence.

Dr. Michael Mugavero

"Measuring retention in HIV primary care is complex, as care includes multiple visits scheduled at varying intervals over time," explained lead author Michael J. Mugavero, MD, from the University of Alabama at Birmingham.

"There has been growing interest into the importance of measuring retention, from a public health and prevention standpoint, but there has not been one standardized way to measure what it means for someone to be retained," Dr. Mugavero told Medscape Medical News.

Two different types of measures have been used, he explained. One is based on the number of kept visits and the other is based on the idea of patients missing visits and not calling ahead to cancel — the no-show visits.

Dr. Mugavero and his team sought to compare these 2 basic measures of patient retention, both in terms of how they relate to each other and how well they predict viral load outcome.

The study involved 10,053 patients who were in care over a 12-month period from May 2007 to April 2008. Individual visit patterns were noted for each patient.

Three retention patterns were categorized as no-show visits: the number of no-show visits accrued; any no-show visit; and the proportion of kept visits to scheduled visits.

Three retention patterns were categorized as kept visits: the number of 4-month intervals with at least 1 kept visit; the 6-month gap, in which 189 days or more elapsed between sequential kept visits; and the Health Resources and Services Administration HIV/AIDS Bureau (HRSA HAB) measure, which denotes 2 kept visits separated by 90 days or more.

The mean age of the patients was 46 years, 65% were male, 64% were black, and 49% were heterosexual.

Wide Range of Visit Adherence

On average, there were 1.5 ± 1.7 no-show visits during the study period; two thirds of patients had at least 1 no-show visit. Nearly half of the patients attended less than 75% of their scheduled clinic appointments, 50% attended visits in all three 4-month intervals, one third had a 6-month gap, and about 25% of patients were not retained, according to the HRSA HAB measure, Dr. Mugavero reported.

Of the study patients, 8235 (82%) had 12-month viral load measures; of these, 6304 (77%) achieved suppression (viral load below 400 copies/mL).

The researchers found that, overall, there was considerable variability among the 6 measures in categorizing patients as being retained (Spearman's correlation coefficient range, 0.16 to 0.85).

However, all 6 retention measures demonstrated strong and statistically significant associations with 12-month viral load suppression (P <.001).

"Accordingly, our data suggest there is no clear gold standard to measure retention in care, and that any of the evaluated measures may have a role, depending on visit data availability, the questions being addressed, the principal rationale, and goals of measuring retention," Dr. Mugavero said.

"These 2 basic types of measures — no-show and kept — seem to be measuring something different in terms of behaviors, yet they both have important information and are strongly predictive of viral load suppression," he said.

The results of this study provide insight into the tools clinicians have to measure retention and adherence, and how to use them, Dr. Mugavero added.

He suggested that researchers might want to choose one measure that includes no shows and one measure that includes kept visits when they plan future studies.

"They might complement each other. They are measuring something different but both are giving important predictive information. Because there is no gold standard or best way to do this, it might be good to measure one of each and include both in research," Dr. Mugavero said.

Dr. José Zuniga

José M. Zuniga, PhD, MPH, from the International Association of Physicians in Washington, DC, and cochair of the conference, commented on this study for Medscape Medical News.

"These data suggest that there is a need for additional research in this field to help define the most precise measures of retention in care. A significant limitation is that the study does not look at retention risk for newly diagnosed patients or those newly entering care," he said.

The study was supported by the Centers for Disease Control and Prevention and the Health Resources and Services Administration. Dr. Mugavero reports financial relationships with Bristol-Myers Squibb, Gilead Sciences, Merck Foundation, Pfizer, Tibotec Therapeutics, and Definicare. Dr. Zuniga has disclosed no relevant financial relationships.

7th International Conference on HIV Treatment and Prevention Adherence: Abstract 79956. Presented June 4, 2012.


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