Does Polypharmacy Lead to Nonadherence or Nonadherence to Polypharmacy?
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See related article, pp 1113–1120
As Gupta et al,1 Tomaszewski and collaborators describe that patient adherence is a major problem for controlling blood pressure (BP) and is difficult to accurately assess in practice and research. One method for assessing adherence is to biochemically detect prescribed BP medications or metabolites in blood or urine samples. There is increasing interest in this method because it has already identified very high levels of nonadherence in hypertension referral centers in Europe and the United States.
The article by Gupta et al1 reports on the largest sample to date of patients tested biochemically for adherence. They found that the strongest predictor of nonadherence is the number of medications prescribed. Other predictors are being female and a younger age. On the basis of their data, the authors propose a predictive model for detecting nonadherence in settings where biochemical testing is unavailable, and they postulate that the use of fixed-dose combinations of antihypertensives, which can reduce the numbers of pills prescribed, may alleviate nonadherence. These are all noble goals and, to many, seem both intuitive and benign. However, a few caveats and limitations emphasize that further study is critical before any clinical implementation is attempted.
The generalizability of the model presented is severely limited by the sample from which it was derived. The key observation (ie, that nonadherence is associated with the number of medications) came from patients who were referred to a specialty center for suspected nonadherence, presumably because of poor BP control. What type of patients would typically be referred to this type of study? A practicing MD likely would not refer the following patients to …