Are people with HIV sticking to their medication treatment regimens? New method measures patient adherence

How do doctors know that patients are taking their medications faithfully? How can physicians help patients stay on lifesaving drugs?

In one of the most in-depth studies of its kind, UCLA researchers found that combining three measurement tools for estimating adherence to drug regimens � including an electronic pill bottle cap that provides a dated record � gives physicians and researchers a more accurate picture of how faithfully patients stay on their prescribed treatments than ever before.

The study, reported in the May 15 issue of the Annals of Internal Medicine, may help physicians and researchers develop new ways to measure medication adherence as well as to develop interventions to help people with HIV and other chronic diseases stay on treatment. Patient non-adherence costs the nation nearly $100 billion annually.

Researchers worked with 108 HIV-infected adults taking protease inhibitors and other highly potent drugs that suppress the HIV virus. Every month for a year, researchers compared three methods of measuring patient adherence to see which most accurately reflected how patients behaved.

The first two methods included asking patients how well they followed the treatment regimen and counting the number of pills remaining in patients� medication bottles. The third method used a special pill bottle cap with a microchip that automatically recorded each time the bottle was opened.

Researchers found that combining all three methods together to generate a special composite adherence score proved more accurate than using each adherence measure by itself.

The study revealed that after taking antiretroviral drugs for six months, patients with undetectable levels of HIV were taking their medication as prescribed about 85 percent of the time. But those with detectable virus blood levels took their pills only about 66 percent of the time. Overall adherence for the full group was 76 percent.

�Patient adherence to medication is critical, especially for patients with HIV,where skipped doses can quickly lead to the virus becoming resistant to the medication,� said Dr. Honghu Liu, lead study author and associate professor, UCLA Division of General Internal Medicine and Health Services Research. �HIV treatments consist of complicated drug regimens, involving many medications taken multiple times each day. As with other chronic diseases, patient adherence plays a major role in successful treatment.�

According to Liu, patient adherence is tough to measure. Each of the currently available adherence measures has its own problems � either over- or underestimating a patient�s true adherence.

�Thisstudy is one of the first with a very rigorous design, aimed to measure adherence in multiple ways over an extended period of time,� Liu said. �We then link the adherence measurements to a clinical outcome � the amount of HIV found in the patient�s blood.�

�The level of non-adherence among the patients in this study is of concern to both the patients and their clinicians,� said Dr. Neil Wenger, study co-investigator and UCLA associate professor, Division of General Internal Medicine and Health Services Research.

The next step, according to Wenger, will be to transform these findings into better, more practical tools to monitor patient adherence. �Better adherence measurements can then lead to better interventions to improve adherence and clinical outcomes.�

The study was funded by the National Institute of Allergy and Infectious Diseases, part of the National Institutes of Health.

Dr. Andrew Kaplan of the University of North Carolina is the principal investigator of the project. Institutions involved in the study include: UCLA Division of General Internal Medicine and Health Services Research; Harbor-UCLA Medical Center; University of North Carolina at Chapel Hill, Sheps Center for Health Services Research, Department of Microbiology and Immunology; and Lineberger Comprehensive Cancer Center.