The Effects of the National Centralized Drug Purchasing Pilot Program on Nucleos(t)ide Analogs in Shenzhen City: An Interrupted Time Series Analysis

Objectives: To assess the effects of the National Centralized Drug Purchasing Pilot Program on nucleos(t)ide analogs (NAs) in Shenzhen city. Methods: Drugs procurement records in medical institutions were analyzed covering the period from January 2018 to December 2019. An interrupted time series (ITS) analysis was used to evaluate the impact of the "4+7" pilot policy on NAs in Shenzhen city. The outcome measures were usage volume, expenditures, daily cost, and distribution structure of NAs. Findings: After the introduction of the "4+7" pilot policy, the defined daily doses (DDDs) of NA drugs increased by 76.48%, the expenditures and defined daily dose cost (DDDc) of NAs decreased by 45.43 and 69.08%, respectively. The proportion of winning products in Entecavir and Tenofovir Fumarate DDDs was increased by 64.21 and 19.20%, respectively. The post-intervention period witnessed a significant increase in the regression level for NAs DDDs (level coefficient: beta(2) = 631.87, p < 0.05). The expenditures (trend coefficient: beta(3) = 392.24, p < 0.05) and DDDc (level coefficient: beta(2) = -6.17, p < 0.001; trend coefficient: beta(3) = -0.21, p < 0.05) of NAs showed decreasing trend in the post-intervention period. The expenditures of original products and generic products both showed a decreasing trend in the post-intervention period (trend coefficient: beta(3) = -372.78, p < 0.05, trend coefficient: beta(3) = -130.78, p < 0.05, respectively). The DDDc of original products in the policy-related varieties was a significant decrease in the regression slope and level (level coefficient: beta(2) = -2.18, p < 0.05; trend coefficient: beta(3) = -0.32, p < 0.01). Conclusion: After the implementation of the"4+7" policy, the DDDc of NAs decreased, the accessibility of policy-related drugs was improved, and the usage of generic medicine was promoted.