Expect the unexpected: a role for behavioral economics in understanding the impact of cost-sharing on emergency department utilization.

BACKGROUND: AS EMPLOYERS AND PAYERS ADDRESS INCREASING HEALTHCARE COSTS, THEY RESORT TO THE TENETS OF CLASSICAL ECONOMICS: if one increases the price for a service (defined as an individual's cost-sharing), then that individual's demand for services should decrease. This, however, may not necessarily be true, and raises the question of whether increased cost-sharing for emergency department services will lead to decreased utilization of those services as would be expected in classical economics.

OBJECTIVE: To assess the effect of emergency department cost-sharing on patient utilization of emergency department services.

METHOD: In 2002, we retrospectively reviewed 2001 claims and identified 797 members who have had at least 2 nonemergent visits to the emergency department. This cohort was comprised of members with high emergency department utilization patterns who also had potentially differing emergency department copayment changes from one health insurance plan year to the next. Participants had to be covered by Humana for a minimum of 12 consecutive months. Of the original cohort, 415 remained covered by Humana after the end of the first year, 322 remained covered after the second year, and 194 after the end of the third year. After completions of three 12-month blocks of time with appropriate claims run out, we assessed changes in the cohort's emergency department encounters from the previous year to the current year relative to emergency department copayment changes, using matched pairs t-test.

RESULTS: Surprisingly, in the first 12 months, reductions in emergency department copayments resulted in decreases in patient utilization (-58.3% change, P <.007), and increases in emergency department copayment resulted in an increased utilization (1096.0% change, P <.001). This unexpected trend continued in the second and third periods. Overall, in our cohort, increases in emergency department copayments were significantly associated with increased emergency department encounters by different individuals in each of the 3 study periods. In contrast, in the 2 groups with no increases in emergency department copayments, utilization of these services decreased or remained flat.

CONCLUSION: When assessing the need for emergency department services, many factors besides cost play a role in choosing to obtain emergency department care, including individual assessments of the probability of a given illness and the financial or temporal implications for the care sought in terms of "gains" or "losses" relative to a reference point. Behavioral economics can therefore play a role in understanding why healthcare consumers behave as they do. The implications of behavioral economics need to be factored in when considering a healthcare benefit design.