Historically, the ability of people with chronic health conditions to take their medication as prescribed and directed, on time, every day — otherwise known as "adherence" or "compliance" — is not good. Skipping a few pills for a few days in a row may not have serious consequences for some people with mildly elevated blood pressure. However, the stakes are much greater in HIV because of the virus' ability to mutate and escape the effects of anti-HIV medication. This can occur when doses are skipped and drug levels fall below the level that keeps HIV suppressed. It is estimated that adherence rates of about 95% are needed by PHAs who are taking highly active antiretroviral therapy (HAART).
The medications available for controlling HIV must usually be taken several times daily and some of them have food and water restrictions. All of them have varying degrees of side effects. Combined, these factors can affect a person's adherence. Other factors can include unstable lifestyles, depression and a lack of psychosocial support.
What do PHAs and their doctors think about the factors that affect adherence? How do doctors measure adherence? To find the answers to these and related questions, researchers in Bonn, Germany, conducted a study.
Researchers conducted standardized interviews about adherence with 98 German doctors. The research team also surveyed 284 PHAs about their views on adherence.
According to the researchers, doctors overestimated adherence levels in their patients. Indeed "only 64% of the doctors always discussed adherence with their patients." The way that the doctors measured adherence was indirect: monitoring the results of blood tests, specifically CD4+ counts and viral load. Few doctors used a standardized questionnaire to assess adherence. When doctors noticed a decrease in CD4+ counts and/or an increase in viral load, then they raised the possibility of adherence difficulties with their patients. If during the discussion adherence was found to be a problem, the solution offered by 83% of the docs was to emphasize the importance of being adherent to HIV medications. According to the researchers, few doctors tried to determine the reasons for difficulties with adherence and offer "additional supportive measures."
The doctors believed that there was a significant connection between being adherent and a patient's "social status and educational level." However, researchers found that this connection to adherence was, in fact, not significant.
In surveying PHAs, the most important factors associated with non-adherence included the following:
Factors associated with being adherent included the following:
Since adherence is an important issue, these findings will be of interest to many people involved in the care and treatment of HIV/AIDS. Given how challenging it is for physicians to keep up-to-date on treatment information and look after many patients with a complex medical condition, it may be unreasonable to expect them to access a valid standardized adherence questionnaire and to constantly administer it to their patients. It is also not fair to expect physicians to carry the burden of adherence support and education. Unmeasured in this research project was the role played by other key members of a PHA's health team in maintaining or enhancing adherence, including:
The pharmaceutical industry also has a role to play in helping to improve adherence. When treatments first became available, they had to be taken three or more times daily. With combination therapy now the standard of care, this can mean multiple pills many times a day. Fortunately, several drugs are now being combined into a single pill, examples being:
Results of satisfaction surveys presented at the conference found that users of simple treatment regimens such as Trizivir (taken twice daily) reported relatively higher rates of satisfaction than those who are on regimens that consist of more pills.
To help reduce "pill burden," new formulations of existing drugs, such as ddI, are being made into once-daily pills — Videx EC. A similar change is underway for d4T (Zerit), and efavirenz (Sustiva) is now available in a single tablet.
Two protease inhibitors should be available in once-daily formulations in 2003 — atazanavir and fos-amprenavir (the new version of amprenavir [Agenerase]).
All of these innovations are important and help to reduce barriers to adherence. But future work still needs to be done on developing combination therapy with fewer side effects.
REFERENCES
Weilandt C and Rockstroh J. Adherence: providers versus patients views of associated factors and intervention approaches. Sixth International Congress on Drug Therapy in HIV Infection, 17-21 November 2002, Glasgow. Poster 90.
Gatti A, Arpinelli F, Visona G, et al. Impact of less complex HIV-therapy on adherence and quality of life-ADEQUA survey. Sixth International Congress on Drug Therapy in HIV Infection, 17-21 November 2002, Glasgow. Poster 96.
Jordan J, Delea T, Sherrill B, et al. Impact of fixed-dose combination zidovudine/lamivudine on adherence to antiretroviral therapy: a retrospective claims-based cohort study. Sixth International Congress on Drug Therapy in HIV Infection, 17-21 November 2002, Glasgow. Poster 97.
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