Increase in Potential Low-value Magnetic Resonance Imaging Utilization Due to Out-of-pocket Payment Reduction Across Income Groups in Korea: An Experimental Vignette Study

OBJECTIVES: This study examined the effect of out-of-pocket (OOP) payment reduction on the potential utilization of low-value magnetic resonance imaging (MRI) across income groups. METHODS: We conducted an experimental vignette survey using a proportional quota-based sample of individuals in Korea (n=1229). In two hypothetical vignettes, participants were asked whether they would be willing to use MRI if they had uncomplicated headache and non-specific low back pain, each before and after OOP payment reduction. To account for the possible role of physician inducement, half of the participants were initially presented with vignettes that included a physician recommendation for low-value care. The predicted probability, slope index of inequality (SII), and relative index of inequality (RII) were calculated using logistic regression. RESULTS: Before OOP payment reduction, the lowest income quintile was least likely to use low-value MRI regardless of physician inducement (36.7–49.6% for low back pain; 30.5–39.3% for headache). After OOP payment reduction, almost all individuals in each income quintile were willing to use low-value MRI (89.8–98.0% for low back pain; 78.1–90.3% for headache). Absolute and relative inequalities concerning potential low-value MRI utilization decreased after OOP payments were reduced, even without physician inducement (SII: from 8.15 to 5.37%, RII: from 1.20 to 1.06 for low back pain; SII: from 6.99 to 0.83%, RII: from 1.20 to 1.01 for headache). CONCLUSIONS: OOP payment reduction for MRI has the potential to increase low-value care utilization among all income groups while decreasing inequality in low-value care utilization.