Influence of Chinese National Centralized Drug Procurement on the price of policy-related drugs: an interrupted time series analysis

BACKGROUND: The Chinese government implemented the first round of National Centralized Drug Procurement (NCDP) pilot (so-called “4 + 7” policy) in mainland China in 2019. This study aims to examine the impact of “4 + 7” policy on the price of policy-related drugs. METHODS: This study used drug purchasing order data from the Centralized Drug Procurement Survey in Shenzhen 2019, covering 24 months from January 2018 to December 2019. “4 + 7” policy-related drugs were selected as study samples, including 25 drugs in the “4 + 7” procurement list and 57 alternative drugs that have an alternative relationship with “4 + 7” List drugs in clinical use. “4 + 7” List drugs were then divided into bid-winning and bid-non-winning products according to the bidding results. Single-group Interruption Time Series (ITS) analysis was adopted to examine the change of Drug Price Index (DPI) for policy-related drugs. RESULTS: The ITS analysis showed that the DPI of winning (− 0.183 per month, p < 0.0001) and non-winning (− 0.034 per month, p = 0.046) products significantly decreased after the implementation of “4 + 7” policy. No significant difference was found for the immediate change of DPI for alternative drugs (p = 0.537), while a significant decrease in change trend was detected in the post-“4 + 7” policy period (− 0.003 per month, p = 0.014). The DPI of the overall policy-related drugs significantly decreased (− 0.261 per month, p < 0.0001) after “4 + 7” policy. CONCLUSIONS: These findings indicate that the price behavior of pharmaceutical enterprises changed under NCDP policy, while the price linkage effect is still limited. It is necessary to further expand the scope of centralized purchased drugs and strengthen the monitoring of related drugs regarding price change and consumption structure. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12889-021-11882-7.