Impact of drug cost sharing on service use and adverse clinical outcomes in elderly receiving antidepressants.

BACKGROUND: Depression imposes enormous burdens on the elderly. Despite this, rates of initiation of and adherence to recommended pharmacotherapy are frequently low in this population. Although initiatives such as the Medicare Modernization Act (MMA) have improved seniors' access to antidepressants, there are concerns that the patient cost-sharing incorporated in the MMA may have unintended consequences if it reduces essential drug use. Age-related pharmacokinetic and pharmacodynamic changes could make seniors particularly vulnerable to antidepressant regimens used inappropriately to save costs, increasing their risks of morbidity, hospitalizations, and nursing home placements. Two sequential large-scale "natural experiments'' in British Columbia provide a unique opportunity to evaluate the effect of cost sharing on outcomes and mental health service use among seniors. In January 2002 the province introduced a CAD 25 copay (CAD10 for low-income seniors). In May 2003 this copay policy was replaced by a second policy consisting of an income-based deductible, 25% coinsurance once the deductible was met, and full coverage once an out-of-pocket ceiling was met. The transition between the two policies is analogous to what many U.S. seniors experience when they transition from private insurance requiring copays to Medicare Part D requiring deductibles and coinsurance. AIMS: To evaluate whether declines in antidepressant initiation after the introduction of two drug cost-sharing policies in British Columbia were associated with increased use of physician services, hospitalizations, and nursing home admissions among all British Columbia residents aged 65+.
METHODS: Records of physician service use, inpatient hospitalizations, and residential care admissions were obtained from administrative databases. Population-level patterns over time were plotted, and effects of implementing the cost-sharing policies examined in segmented linear regression models.
RESULTS: Neither policy affected the rates of visits to physicians or psychiatrists for depression, hospitalizations with a depression diagnosis, or long-term care admissions. DISCUSSION: The cost-sharing policies studied may have contained non-essential antidepressant use without substantially increasing mental health service utilization. However, it is possible that the policies had effects that we were unable to detect, such as increasing rates of visits to social workers or psychologists or forcing patients to reduce other spending. Further, the sequential implementation of the policy changes, makes it difficult to estimate the effect of a direct change from full coverage to a coinsurance/income-based deductible policy. IMPLICATIONS FOR HEALTH POLICIES: It may be possible to design policies to contain non-essential antidepressant use without substantially increasing other service utilization or adverse events. However, because undertreatment remains a serious problem among depressed elderly, well-designed prescription drug policies should be coupled with interventions to address under-treatment.