Why Don't Patients Fill Prescriptions? A Study Examining Primary Nonadherence

Jayashri Sankaranarayanan, MPharm, PhD


May 06, 2010

Primary Medication Non-Adherence: Analysis of 195,930 Electronic Prescriptions

Fischer MA, Stedman MR, Lii J, et al
J Gen Intern Med. 2010; 25:284-290

Study Summary

The authors from Boston's Brigham and Women's and Massachusetts General Hospitals assessed primary nonadherence, or failure to fill new prescriptions, to identify factors that predict nonadherence. This retrospective study evaluated claims data for 195,930 electronic prescriptions (e-prescriptions) written over a 12-month period. The data came from 75,589 patients treated by 1217 prescribers in the first year of community-based practices that had adopted stand-alone e-prescribing systems. For all e-prescriptions and new medication beginnings, the authors calculated primary adherence rates as the number of prescriptions filled divided by the total number of e-prescriptions. Patient and medication characteristics were compared and characteristics associated with nonadherence were examined.

About 22% of all e-prescriptions and 28% of e-prescriptions for new medications were not filled. Primary adherence rates were higher for e-prescriptions from primary care specialists (internal medicine, family practice, pediatricians). Patients aged 18 and younger filled prescriptions at the highest rate (87%). Primary adherence was lower if the prescriber gender was female, prescriber age was young, and practice sizes were large. Medication class strongly predicted adherence in multivariate analyses. Patients on newly prescribed medications for chronic conditions were often nonadherent. Newly prescribed e-prescriptions were not filled for antihypertensive medications (28%), lipid-lowering agents (28%), and antidiabetic medications (31%).


Doctors write about 3.8 billion prescriptions every year.[1] A large concern about the quality of healthcare in the United States is the underuse of prescription medicines.[2] Underuse could result from under-diagnosis, under-treatment, or medication nonadherence.[3]

Medication nonadherence to essential medications results in greater morbidity (ie, disease progression, disease complications, reduced functional abilities, a lower quality of life) and mortality.[4,5] According to the World Health Organization, approximately 50% of all patients are nonadherent to medications.[1,5] In the United States, medication nonadherence results in more than $100 billion spent each year on avoidable hospitalizations[1,3] and about $177 billion yearly in total direct and indirect healthcare costs.[5]

The potential burden of medication nonadherence outcomes on healthcare delivery makes it an important public health concern. However, examining fill rates of new prescriptions almost always handwritten (until recently) is costly and difficult. Per the authors, small samples and use of patient surveys limit the findings of previous primary medication nonadherence reports of 4%-22%.

To improve the quality of patient care by reducing medication errors, the Medicare Modernization Act of 2003 wanted drug insurance plans taking part in the new prescription benefit (Medicare Part D) to support e-prescribing. With e-prescribing, doctors can electronically send an accurate and legible prescription directly to a pharmacy from their point-of-care. This study shows how e-prescribing data connected to filled claims data enables measuring of primary nonadherence which was not possible earlier.

The authors recognize study limitations that make it difficult to generalize their findings to other larger integrated healthcare settings. For example, the study may have underestimated nonadherence by including only early e-prescribing adopters and excluding non e-prescriptions and actions taken by patients, providers, and pharmacists. Further, the authors could have misclassified adherent patients who paid cash or filled prescriptions at other locations as nonadherent and thereby overestimated nonadherence.

Despite limitations, this study offers information on medication nonadherence and its related predictors. This can help providers tailor interventions to encourage patients to begin newly prescribed therapy and continue therapy. These efforts can help realize the potential of e-prescribing for improving the effectiveness and quality of prescription drug care and also reduce the cost of long-term adverse results of medication nonadherence.



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