OBJECTIVES : In South Korea, the government had set a fixed daily upper limit of medical expenses for outpatient visits of patients with mental disorders (MD) in the Medical Aid (MA) program. Due to this policy, there was inequality in the use of prescribed drugs. Thus, in March 2017, the government implemented the new policy named the Comprehensive Plan on Mental Health Act, which is no fixed daily upper limit. I aimed to determine the impact of the new policy on the cost of drug prescription among pediatric patients with MD in the MA program compared to those in the non-MA program.

METHODS : Between 2015 and 2017, pediatric patients with MD were defined as those aged < 20 years for outpatient visits at least twice in a year with an MD (F code of ICD-10^th) as a primary diagnosis from Korea Health Insurance Review and Assessment agency – Pediatric Patients Sample data. Prescription data were aggregated quarterly and the average drug costs were calculated. An interrupted time series analysis examined the impact of the new policy on a trend in the outcome of the daily average drug cost. Autoregression was tested by Durbin-Watson statistics (DWS).

RESULTS : A total of 15,517 prescription bills (2,430 patients) for the MA and 403,895 bills (55,833 patients) for the non-MA program was included. After the implementation, the drug cost was increased at 1.9 times (after $45 vs. before $24) in the MA program. Contrarily, in the non-MA program, there was no statistically significant change (after $37 vs. before $39). The results of segmented regression analysis confirmed that the new policy had an impact on the increase of the average drug cost (beta=36.7, p<0.01) with no autoregression (DWS=2.2).

CONCLUSIONS : This result implies the new policy for MA patients had an immediate impact. To assess the long-term impact, further studies are needed.