Nonadherence with medication regimens may result in increased use of medical resources, such as physician visits, laboratory tests, unnecessary additional treatments, emergency department visits, and hospital or nursing home admissions. Nonadherence may also result in treatment failure.
In the context of disease, medication nonadherence can be termed an "epidemic." More than 10% of older adult hospital admissions may be due to nonadherence with medication regimens (Vermiere et al., 2001). In one study, one-third of older persons admitted to the hospital had a history of nonadherence (Col et al., 1990). Nearly one-fourth of nursing home admissions may be due to older persons' inability to self-administer medications (Strandberg, 1984). Problems with medication adherence were cited as a contributing factor in more than 20% of cases of preventable adverse drug events among older persons in the ambulatory setting (Gurwitz et al., 2003). It is estimated that nonadherence costs the US health care system $100 billion per year (Vermiere et al., 2001). In addition, approximately 125,000 deaths occur annually in the US due to nonadherence with cardiovascular medications (McCarthy, 1998).
Of all age groups, older persons with chronic diseases and conditions benefit the most from taking medications, and risk the most from failing to take them properly. Among older adults the consequences of medication nonadherence may be more serious, less easily detected, and less easily resolved than in younger age groups (Hammarlund et al., 1985).
Improving adherence with medication regimens can make a difference. A recently published study found that for a number of chronic medical conditions - diabetes, hypertension, hypercholesterolemia, and congestive heart failure - higher rates of medication adherence were associated with lower rates of hospitalization (Figure 1), and a reduction in total medical costs (Sokol et al., 2005).