OBJECTIVES: Diabetic macular edema (DME) is a fatal disease that causes blindness. The recently reimbursed drugs, ranibizumab and aflibercept, are effective but expensive. This study aimed to analyze the economic impact in an experimental setting before and after reimbursement of the expensive drug in DME.

METHODS: A retrospective cohort study incorporating the Exponential Conditional Model (ECM) with gamma distribution was conducted using Seoul National University Bundang Hospital Observational Medical Outcome Partners-Common Data Model data. Patients with diabetic macular edema were in the treatment group between July 1, 2004, and July 31, 2017. The control group was diabetes patients in the same period. Propensity score matching was performed including index year by LASSO in ATLAS. Demographic data, cohort group, pre-index cost, reimbursement date, and unbalanced covariates in the propensity score model were included for covariates in the ECM. Outcomes for the ECM were total medical cost, insurance benefit cost, and out-of-pocket expenses for three years.

RESULTS: After propensity score matching and the ECM, total medical cost, insurance benefit cost, and out-of-pocket expenses for three years were significantly higher than the control group (p<0.01). The incremental total medical cost was estimated at 1,706$ before and 2,959$ after reimbursement. It was 34.21% more than the control group after reimbursement (p=0.080). The insurance benefit cost was increased by 41.31% for the DME group after reimbursement (p=0.178). For out-of-pocket expenses, incremental cost was 30.73% compared control group after reimbursement (p=0.053).

CONCLUSIONS: Despite the reimbursement of expensive drugs in DME, the economic impact on payers was not significantly increased. The patient's disease burden is also increased through active and various treatments due to reimbursement. However, to evaluate the precise effect of reimbursement policy, we need to consider the economic impact on various aspects, including clinical effectiveness after reimbursement.