Interrupted time series analysis of chronic periodontitis‐related procedures before and after the scaling reimbursement policy in Korea

Aim To study the use of a quasi‐experimental design to assess the effects of scaling reimbursement policies on the incidence of chronic‐periodontitis procedures. Materials and Methods Interrupted time series analysis was used to compare the effects before and after policy implementation using data on the number of periodontitis‐related procedures from the Korean National Health Insurance Service‐National Sample Cohort ( n = 740,467) and the Health Screening Cohort ( n = 337,904). Periodontitis‐related procedures with diagnosis codes were categorized into basic (scaling or root planing), intermediate (subgingival curettage) and advanced (tooth extraction, periodontal flap surgery, bone grafting for alveolar bone defects or guided tissue regeneration). Subjects' demographics and comorbidities were considered. The incidence rate of immediate changes and gradual effects before and after policy implementation was assessed. Results Following the policy implementation from July 2013, an immediate increase was observed in total and basic procedures. No significant changes were noted in intermediate and advanced procedures initially. A decrease in the slope of intermediate procedures was observed in both databases. Advanced procedures showed varied trends, with no change in the National Sample Cohort but an increase in the Health Screening Cohort, particularly among subjects with comorbidities. Conclusions Following the new policy implementation, the number of intermediate procedures decreased while the number of advanced procedures increased, especially among patients with comorbidities. These findings offer valuable insights on policy evaluation.