Assessing adherence to statin therapy using patient report, pill count, and an electronic monitoring device

Lack of patient adherence to prescribed drug regimens is an important medical issue, especially for patients with chronic illnesses. The financial burden of nonadherence has been estimated to cost 100 billion each year in the United States. 1 Atherosclerotic cardiovascular diseases are a major cause of morbidity and mortality in industrialized countries. Heart disease is the second most common cause of death in Hong Kong, and coronary heart disease (CHD) accounts for the majority of deaths from heart disease. 2–, 4 Hydroxymethylglutaryl–coenzyme A (HMG-CoA) reductase inhibitors (statins) show potent effects on lowering low-density lipoprotein (LDL) cholesterol levels and have demonstrated significant reduction in CHD-related morbidity and mortality. 5–, 7 Adherence to statin regimens is critical for the prevention of CHD. 8, 9 However, suboptimal lipid control is widely observed in clinical settings, suggesting a discrepancy in patient adherence to statin therapy between controlled clinical trials and routine practice. 10, 11 While various methods are used to assess adherence to drug regimens, such as pill count, patient’s self-reports, pharmacy dispensing records, and the measurement of serum drug or drug metabolite levels, most of these approaches are limited to some degree. 12–, 15 In Hong Kong, a majority of the residents receive medical care from a government-funded public health agency. Medications prescribed in outpatient clinics of public hospitals cost patients HK10 (US1 = HK7. 8) per prescription for a four-month supply, and pharmacy dispensing records very often show 100% adherence to filling prescriptions.