摘要：Objectives. We sought information about the cost-related underuse of medications—which medications are underused, by whom, and how often. Methods. Chronically ill adults were asked to identify how often they underused prescription medication for 16 health conditions because of the cost. Results. Eighteen percent of respondents cut back on medication use owing to cost in the previous year, and 14% used less medication at least monthly. Although rates of underuse varied substantially across treatments, prescription coverage and out-of-pocket costs were determinants of underuse across medication types. Conclusions. Many chronically ill adults frequently cut back on medications owing to cost. Patients are selective about the treatments they forgo. Out-of-pocket costs and inadequate prescription coverage may lead to adherence problems for many important medication types. Many chronically ill patients take less of their medication than has been prescribed, owing to cost concerns, especially those patients with low incomes, multiple chronic health problems, or no prescription drug coverage. 1– 3 The consequences of cost-related medication underuse include increased emergency department visits, psychiatric admissions, and nursing home admissions, as well as decreased health status. 4– 6 Although the public health significance of cost-related medication underuse is becoming clear, we have only a limited understanding of how medication costs affect individuals with differing clinical and socioeconomic characteristics. Recent survey-based studies 1, 2 asked respondents to report on cost-related adherence problems without specifying individual treatment types. As a result, investigators have had only a limited ability to identify which medications patients are most likely to underuse. Approximately 73% of older adults who use prescription medications use more than 1, and 29% use 4 or more. 7 Although the clinical significance of cost-related underuse is different when patients cut back on treatment for life-threatening asymptomatic illnesses (e.g., hypertension) versus disabling symptomatic conditions (e.g., back pain), it is unclear whether those who restrict their medication use do so uniformly or are selective in which treatments they forgo. In addition, previous studies that used global measures assume that individuals reporting cost-related underuse are describing a regular practice, rather than isolated events. However, there has been little research to determine whether this assumption is accurate. The paucity of data on cost-related medication adherence problems has important implications not only for estimating their clinical significance, but also for understanding the extent to which adherence problems vary across socioeconomic groups. For example, non-White patients may be more likely than Whites to discontinue pharmacotherapy for depression, 8 and thus may be especially likely to forgo antidepressant treatment when facing cost pressures. However, general measures of medication underuse may miss problems specifically associated with antidepressants or other therapeutic categories. In addition, global estimates of the relationship between out-of-pocket costs and underuse may mask important differences across treatments. Individuals may be more sensitive to cost pressures when taking medications that they perceive as having little impact on their health or longevity, while patients who believe that their treatment is essential might maintain high levels of adherence despite high costs. For all of these reasons, policymakers and clinicians need more extensive information about chronically ill patients’ cost-related underuse of prescription medications. Accordingly, we surveyed chronically ill adults to ascertain the prevalence, frequency, and risk factors for cost-related medication adherence problems. The study builds on previous research by describing (1) the relationships among global measures of cost-related medication underuse, measures documenting underuse of specific treatments, and measures identifying individuals who frequently experience adherence problems; and (2) variation in the importance of socioeconomic risk factors for underuse across treatment types.
