November 27, 2012
Mathieu Bastard et al. PLoS ONE; 7(11): e49091. Read the full text.
Predicting adherence to medications is a fool's game. Who knows how many patients I have seen -- smiley people with winning personalities, some of whom even send me holiday cards -- who I would wager are great at taking their meds, yet who secretly end the month with more than a few extra tablets in their bottles. Most of these folks are lucky in that their viral loads are as suppressed as their mischief, but their non-adherence can catch up with them.
The most common method to assess adherence is to ask people about missed doses, which is helpful only when the beans are spilled; otherwise, such a survey method is useless (see the next summary for more on this). There are some nifty ways to gauge adherence, including pill counts, pharmacy refills and checking drug levels in blood or even hair. However, these are not perfect, nor are they always practical and available.
Investigators from Médecins Sans Frontières (MSF) looked at something much more simple: whether patients had delays in making their clinic appointments. They calculated a metric of the number of appointments attended, with lateness (in days) divided by the number of months between ART initiation and date of virological testing, and then multiplied the result by 100 (simple!). Applying this metric, they categorized 3,580 adults and 253 children receiving care at MSF clinics in Africa and Asia as "good," "moderate" or "poor" adherers to clinic appointments.
In their analysis, 58.0% of patients showed good adherence, 35.6% showed moderate and 6.4% showed poor. Patients in the poor and moderate categories were two to three times more likely to experience virological failure and HIV drug resistance compared to those within the good category -- even after adjusting for initial age and CD4+ cell count, previous ART experience, type of regimen and tuberculosis diagnosis at start of therapy. Results were similar in children. Interestingly, the delays in making it to an appointment at an MSF clinic were not huge -- they were generally on the order of a few days.
It can be debated whether these results, obtained from facilities in some of the poorest places on Earth, can be translated to our more cushy world of flat screen-equipped waiting rooms and automated appointment reminders here in the U.S. However, I suspect the same concepts apply -- and, although the forces that make getting to a doctor's appointment a challenge may be different in Burkina Faso than in Buffalo, N.Y., they nonetheless impact medication adherence regardless of geography.
It is the patient who misses visits or shows up late for his/her clinic appointments that we should watch carefully. These data and our own experiences tell us they may be at greatest risk of falling off the ART wagon.
Betsy J Feldman et al. AIDS Behav 2012: epublished ahead of print. Read the abstract.
Looking at your patient's appointment tardiness may be useful, but is likely to be specific and not sensitive to suboptimal medication adherence. The same can be said for self-reported adherence. Although asking folks how well they are taking their meds is standard operating procedure in clinical research, so is fibbing; for most clinicians, their patients' responses are considered about as reliable as those dealing with number of beers drunk and when crack was last smoked (i.e., not).
What if there was a question that patients did respond to and, like Wonder Woman's lasso, revealed all?
A group of collaborators from the CNICS cohort don't have anything nearly so foolproof, but they do suggest that one single question was as good as, or even better than, longer batteries of adherence questions.
They looked at data collected during self-reported assessments completed during routine clinic visits by those on ART who attended clinics in Birmingham, Ala., or Seattle, Wash. These assessments are done using a touch-screen tablet and include surveys of medication adherence, substance/alcohol use and depression. The medication adherence questions include an item that, in at least one study comparing it to the gold standard (electronic caps that record the opening of a medication bottle), was found to produce less overestimation of adherence.
What is this question, you may ask? The way the authors refrain from explicitly reporting it in this paper, you would think it was David Petraeus' personal email account password. Fortunately, I found the actual wording in the paper describing the electronic cap study, and the amazingly revealing question is fiendishly simple: "Rate your ability to take all your medications as prescribed" over the past month (in one of six categories: very poor, poor, fair, good, very good and excellent). That's it.
In the CNICS study, this one question was compared to the other adherence survey items, as well as viral load results, in 2,399 patients. Most patients rated their adherence to be pretty decent, with very few rating their adherence as "poor" or "very poor." Among those reporting poor or very poor adherence, 51% had a detectable viral load; by comparison, a detectable viral load was found among 42% of those reporting fair adherence, 23% of those reporting good adherence, 13% of those reporting very good adherence and 9% of those reporting excellent adherence.
The single-question responses correlated well with other survey items and, in terms of predicting viral load suppression, the single question was just as good as using a visual analogue scale to indicate adherence -- but it was quicker to complete, clocking in at a mean of just 13.5 seconds.
Who knew that asking a direct question could lead to more honest answers? Of course, almost 1 in 10 of those rating their adherence over the past month as "excellent" had a detectable viral load, raising suspicious eyebrows. But the study suggests that we can do away with longer and more cumbersome surveys when this one question is used. At 13.5 seconds, it may be worth a try.
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