Primary Nonadherence to Prescription Drugs Widespread
Abstract & Commentary
By Rahul Gupta, MD, MPH, FACP
Clinical Assistant Professor, West Virginia University School of Medicine, Charleston, WV
Dr. Gupta reports no financial relationships relevant to this field of study.
Synopsis: In a study of primary care patients, primary nonadherence was found to be common and may be improved by eliminating cost barriers as well as more frequent physician visits.
Source: Tamblyn R, et al. The incidence and determinants of primary nonadherence with prescribed medication in primary care: A cohort study. Ann Intern Med 2014;160:441-450.
Nonadherence to medications is a familiar challenge in clinical practice. In the providers’ office, prescriptions are written with the clear expectation that they will be dispensed and taken exactly as prescribed. However, that often does not occur. Nonadherence can be divided into primary and secondary types. Primary nonadherence occurs when the patient fails to initiate the recommended treatment altogether, while secondary nonadherence is used to describe a complex range of situations, such as when the patient intentionally or unintentionally skips doses, uses lower doses than prescribed, or uses medical devices incorrectly.1 Generally, we use the term nonadherence to describe secondary nonadherence where most of the research has been conducted. However, it is critical to be aware of the extent to which primary nonadherence occurs since the rising burden of chronic diseases often imposes a long-term regimen of prescription medications, which if not initiated timely, may lead to an increase in health care costs due to a variety of factors such as frequent emergency room visits, hospitalizations, and the ensuing disability. Moreover, current research suggests that the average Medicare patient with one chronic condition sees four physicians a year, while those with five or more chronic conditions see 14 different physicians a year.2 Failure to fill an initial drug prescription from each of these physicians may have a substantial adverse impact on the health of the patient, while learning the root cause for such may assist in achieving improved clinical outcomes.
In their research, Tamblyn et al studied the incidence of primary nonadherence in primary care practices and the drug, patient, and physician characteristics that are associated with a greater risk for such. In this prospective cohort study from Quebec, Canada, researchers evaluated the incidence and characteristics of primary nonadherence (failing to fill a new prescription within 9 months) using provincial drug insurer data on all drugs dispensed from community-based pharmacies. The study included 15,961 patients receiving 37,506 incident prescriptions in a primary care network of 131 physicians between 2006 and 2009. The researchers found that 31.9% of these new prescriptions were not filled within 9 months after they were written.
More than half of the prescriptions for headache (51.0%) and ischemic heart disease (51.3%) and more than one-third of the prescriptions for depression (36.8%) were not filled. The lowest rate of primary nonadherence was for urinary tract infection (21.0%). As for pharmacological class, the highest incidence of nonadherence was for hormones and synthetics (36.3%), especially with thyroid drugs (49.4%), followed by ear, nose, and throat preparations (34.2%) and cardiovascular drugs (34.7%). The lowest incidence of primary nonadherence was for anti-infectives (24.2%).
Researchers also found that higher medication costs (such as those due to copayments), recent hospitalization, and more severe comorbid conditions resulted in greater risk for primary nonadherence. A significant dose-response relationship was found between drug cost and nonadherence. Compared with patients who were charged the maximum copayment, patients who received free medications were 63% more likely to fill prescriptions (odds ratio [OR], 0.37; 95% confidence interval [CI], 0.32-0.41]). The odds of nonadherence were also reduced by 11% per 10-year increase in age (OR, 0.89; 95% CI, 0.85-0.92]). Patients using a greater number of medications were also more likely to be nonadherent, with a 17% reduction in the odds of nonadherence per additional medication. Interestingly, researchers also found that having more physician visits was associated with lower odds of nonadherence, whereas having a prescription from a female physician was associated with slightly higher odds of nonadherence.
COMMENTARY
This study found that nearly one-third of all initial drug prescriptions were not filled within 9 months. Additionally, the research reveals a number of factors that have an impact on patient medication nonadherence. The risk for primary nonadherence was greater for higher-cost drugs and most chronic preventive therapies compared with antibiotics. Previous studies have shown that almost one-fourth of the e-prescriptions are not filled, with nonadherence being common for newly prescribed medications used for treating chronic conditions such as hypertension, hyperlipidemia, and diabetes.3 Nonadherence to essential medications represents an important public health problem. High rates of primary nonadherence may contribute to potentially preventable complications and more severe comorbid conditions in the population over the long-term. Efforts to increase primary adherence could dramatically improve the effectiveness of disease management efforts with significant cost savings. This research provides a look at various factors that physicians can impact to ensure improved adherence to prescription medications. Lower prescription copayments and a greater proportion of visits with the prescribing physician not only are two factors associated with filling the prescriptions but also provide a better continuity of care. In essence, this may be another reason to prescribe the lowest cost, effective medications, with a preference for least or no copay drugs and stipulate a short-term follow-up visit to assess use and effects.
References
- Pottegård A, et al. Primary non-adherence in general practice: A Danish register study. Eur J Clin Pharmacol 2014;70:757-763.
- Vogeli C, et al. Multiple chronic conditions: Prevalence, health consequences, and implications for quality, care management, and costs. J Gen Intern Med 2007; 22(Suppl 3):391-395.
- Fischer MA, et al. Primary medication non-adherence: Analysis of 195,930 electronic prescriptions. J Gen Intern Med 2010;25:284-290.
