Among people living with HIV, it is almost impossible to predict which of them will best adhere to antiretroviral therapy (ART) medication, said Carlos Del Rio, M.D., a professor of medicine at Emory University School of Medicine. "The first lesson in adherence is that preconceived ideas about who will be adhering and who will not are often wrong," Del Rio said, speaking at IDWeek 2015 in San Diego, California.
There are many factors that contribute to a patient's adherence, and not all are linked to physical barriers, such as proximity to a clinic, poverty or lack of health insurance. Some adherence behavior is linked to patient characteristics, the patient/provider relationship or other medications creating a massive pill burden.
Del Rio noted that medication adherence is extremely important for successful treatment in HIV because without it patients are less likely to be virally suppressed and can develop resistance. This message has been hammered into the collective psyche of HIV treatment providers and patients, and today, people living with HIV do relatively well at taking their meds compared to people with other chronic conditions, Del Rio asserted. For example, people with diabetes have around a 67.5% adherence rate, while the adherence rate in those with HIV is closer to 88%, he said.
Not only are people living with HIV relatively adherent, they are also usually honest about skipping doses or stopping treatment. According to Del Rio, self-reported data is fairly reliable. The most ironclad metric of adherence is viral load (because medication adherence will lead to low viral load), but self-reported data is reliable and easier to obtain. Studies show that self-reported data correlates with viral load, so just asking a patient is probably a good way of gauging his or her adherence, and of collecting adherence data over time, Del Rio said.
During his presentation, Del Rio had some advice for the M.D.s in the audience: "Don't be judgmental," he said. When asking patients about adherence rates, assure them that many people find it difficult to take all their HIV medications exactly as prescribed. Then ask, "How many doses did you miss in the last seven days?" he said.
If a patient is having trouble with adherence, Del Rio advises prescribers to consider switching the patient to medication with a longer half-life, moving to medication that will reduce any side effects the patient is experiencing or reducing the patent's pill burden.
Another successful strategy is treatment counseling, which could include SMS text-message reminders. "Counseling works," Del Rio said. The evidence to support counseling as an intervention is clear, he emphasized.
There is also data to support SMS text messaging, though more studies are needed, Del Rio cautioned. Many experts were hopeful about SMS text-message reminders, but results have been mixed. There is some evidence that texting patients too often could cause them to ignore medication reminders completely, Del Rio said.
Social Model of Adherence
Secrecy and social isolation are challenging barriers to adherence. Whenever possible, clinicians should try to leverage a patient's existing relationships as an extra support system for medication adherence. Del Rio calls this "the social model for adherence."
"I always ask my patients, 'If you were in jail, who would you call to bail you out?' " he said, speaking on the sidelines of the conference. He encourages his patients to open up to that trusted partner, sibling or friend. He advises his patients to bring this person along to their appointments, and to tell him or her about their prescriptions and pill schedule.
This model might be particularly effective in young patients, who find it much more difficult to adhere to medication. The challenge with younger populations, ages 18 to 24, is that only 33% are suppressed, Del Rio said.
There has been very little research looking into which adherence approaches work for adolescents, he said, adding that targeted approaches are needed for adolescents.
PrEP and Early Antiretroviral Therapy
Poor adherence among young patients has significant implications for the success of pre-exposure prophylaxis, or PrEP. Young, uninfected people are usually great candidates for PrEP, but it only works if taken faithfully every day.
"I really think the big Achilles' heel of PrEP could be adherence," Del Rio said, who advised adherence counseling for new patients starting PrEP.
In addition, "early [antiretroviral therapy] adherence is going to be a challenge," Del Rio said. Now that the World Health Organization recommends starting antiretroviral therapy in all newly diagnosed patients, providers are going to face new challenges ensuring that patients with few symptoms adhere to their treatment.
Other Adherence Interventions
Another significant weak link in medication adherence is simply patient retention, Del Rio said. In the United States, half of people linked to care are lost within the first year. Keeping those people looped into the health care system would significantly improve their likelihood of sticking to antiretroviral therapy, he said.
As for other interventions, Del Rio argues that more research is needed. Many experts assumed that offering small payments to patients in exchange for adherence would be an effective tool, but a study called HPTN-065 showed that financial incentives didn't make much of a difference in adherence rates, he said.
"We need to be humble about this," Del Rio said, "We've been wrong many times."
Sony Salzman is a freelance journalist reporting on health care and medicine, who has won awards in both narrative writing and radio journalism. Follow Salzman on Twitter: @sonysalz.