Patient Characteristics Associated with Medication Adherence

The lack of adherence to prescribed medication is an important health challenge. Despite evidence indicating the therapeutic benefit for adhering to a prescribed regimen, many patients do not take medications as prescribed. Several studies have been conducted examining medication adherence for various conditions, and adherence has consistently been found to be suboptimal.1–7 Failure to take medication as prescribed increases the risk that patients will not get the intended benefit, often leading to negative sequelae.3,8–12 Further, not adhering to one’s prescribed medications is likely to result in higher healthcare costs overall.10 Thus, understanding factors associated with maintaining one’s medication regimen is important to patients, providers, and health plans. External factors such as cost and access to the needed medication play a role in non-adherence. However, within our integrated health care system, where most patients have access to care, a covered pharmacy benefit, and easy access to pharmacies, one might expect a lower rate of non-adherence than in the general population. Pharmacies are available in all clinics owned by the medical group. In addition, phone-in, mail order, and internet prescription refill options allow patients the ability to order medications 24 hours a day. Nevertheless, the health system has identified non-adherence as a major area of concern. While the literature has reported some evidence of variation of adherence by age, race, co-morbidity status, and socioeconomic status (SES) (higher adherence in those older, white, lower co-morbidity, and higher SES),8,9,13–17 the majority of studies conducted have examined adherence within a given disease state. Few have examined adherence across multiple conditions to determine whether associations between adherence and patient characteristics are consistent. Such information could be helpful in health systems such as ours to develop focused interventions. Therefore, to increase the understanding of medication adherence in our population, we examined adherence across multiple health conditions, examining associated patient and drug-related characteristics. The purpose of this paper is to report on the patient characteristics associated with adherence within this large integrated health system.