In this study of a large general population of seniors, a decline in antidepressant initiation that occurred after implementing a copay policy(25
) was not associated with increased use of psychiatrist and other physician services or increased hospitalizations for depression and nursing home admissions. Likewise, reductions in the growth of antidepressant dispensing and initiation after substituting a coinsurance/deductible policy were not associated with increases in these service utilization or adverse event outcomes.
Studies that do not find statistically significant changes merit special attention to their statistical power to detect a clinically meaningful change(28
). The results of our analysis indicate that we can exclude a copay policy effect on physician visits for depression greater than an increase of 0.92 visits per 1,000 seniors (507 visits per month among all seniors) and a coinsurance effect of an increase greater than 0.8 visits per 1,000 seniors (446 visits among all seniors) with a confidence level of 95%. Similarly our results exclude with a confidence level of 95% an increase of more than 0.12 hospitalizations with a depression diagnosis / 1,000 seniors (65 hospitalization per month among all seniors) under the copay policy and an increase of more than 0.09 / 1,000 seniors (50 hospitalizations per month among all seniors) under the coinsurance policy(29
). It is difficult to predict what size effect the previously observed reductions in antidepressant initiation and use might have on physician visits and hospitalizations. For example, monthly rates of antidepressant use decreased by 14 patient-days per 1000 seniors per month under the co-insurance policy. This could correspond to 0.5 fewer patients per 1000 receiving any treatment or a number of patients becoming less adherent. In addition, while there is evidence to suggest that non-persistence may be associated with higher medical costs, these data are relatively limited(30
). However, it is possible that small changes occurred and were simply too small to be detected in the current study.
The results of earlier studies on a variety of drug-cost sharing policies have been mixed. Some cost-sharing policies have not been found to increase other health care utilization or adverse events(33
); other policies limiting reimbursements for prescription drugs have been found to increase these unintended consequences(41
), in some cases dramatically(24
). Understanding why specific cost-sharing mechanisms can have such different impacts on utilization, health, and economic outcomes is crucial for designing sound prescription drug policies in the future.
Several potential mechanisms might explain how the cost-sharing policies examined in this study could apparently decrease utilization and initiation of a therapeutic medication, without increasing other service use and unintended consequences(43
). One possibility is that due to potentially high demand and long waiting lists for mental health services, increased needs may not have translated into more utilization especially of ambulatory services. However arguing against this possibility is our finding that adverse consequences requiring urgent attention such as hospitalizations or long-term care, also did not increase.
Another possibility, which is a desired outcome of benefit managers, is that the policies were able to selectively decrease non-essential antidepressant use but spare essential use. Likewise, the policies may have reduced use of poor quality or ineffective antidepressant regimens while leaving intact use of effective ones. Findings from several prior studies support the hypothesis that cost-sharing can reduce inappropriate medication use.(44
) Finally, generous exemption rules for patients and prescribers that accompanied both policies may have helped them achieve their desired effects while minimizing unintended consequences.
These results should be interpreted with several potential limitations in mind. First, it is possible that the cost-sharing policies had unintended impacts on elderly antidepressant users that we were unable to detect. For example, the policies may have driven up the use of other mental health (e.g., psychotherapy visits to non-psychiatrists) or general medical services (e.g., emergency room visits). Likewise, elderly patients may have had to obtain their antidepressant medications by borrowing or by doing without other essential drugs, other forms of health care, and even non-health care necessities (e.g., food, utilities).
Because of the sequential implementation of the policy changes, it is difficult to estimate the effect of a direct change from full coverage to a coinsurance/income-based deductible policy. Although we compared trends during the income-based deductible policy with those during the baseline policy, patterns after the income-based deductible period may have been affected by the introduction of the copay policy. The other comparisons we made—of the coinsurance/income-based deductible policy compared with the copay policy—may underestimate the impact of a because some patients who would have experienced “sticker shock” after the income-based deductible policy went into effect may already have done so after the transition from the full-coverage policy to the copay policy.
A final limitation worth considering is our lack of a concurrent control group. Because the policy changes affected all seniors in British Columbia (with the exception of noncomparable populations, such as seniors residing in nursing homes), no appropriate concurrent control group exists. The validity of an uncontrolled time trend analysis such as ours rests on the assumption that no changes resulting from other interventions or changes in the population occurred at the same time as the interventions of interest.
With these potential limitations in mind, it appears that implementing the two forms of cost-sharing studied here—a copay policy followed by substitution with an income-based deductible/coinsurance policy—may have successfully contained non-essential antidepressant use without substantially increasing other service utilization or adverse events. However it is important to keep in mind that care of depression among the elderly continues to suffer from the dual problems of both non-essential use as well as undertreatment, with the latter being by far the greater public health and public policy concern(8
). It is unlikely that cost-containment policies alone, no matter how clinically and fiscally sound, would increase utilization of treatments by those with unmet needs. Instead, model programs of screening, outreach, and enhanced care have been developed and proven successful at overcoming barriers to care and improving clinical outcomes among elderly persons with undertreated depression(45
). Such programs, together with well-designed prescription drug policies, may ultimately be needed for extremely vulnerable older populations with mental disorders.