The impact of “4+7” volume based drugs procurement on the volume, expenditures, and daily costs of antihypertensive drugs in Shenzhen, China: a interrupted time series analysis

Abstract Background: On January 2019, Chinese government implemented the first round of the National Centralized Drug Procurement (NCDP) pilot of 25 drugs in 4 municipalities and 7 sub-provincial cities in mainland China, referred to as “4+7” policy. In the “4+7” policy, 7 antihypertensive drugs were included. This study was conducted to evaluate the impact of “4+7” policy on the use of policy-related antihypertensive drugs. Method: This study applied single-group Interrupted Time Series (ITS) design. We used drug purchasing data from the Centralized Drug Procurement Survey in Shenzhen 2019, covering 24 months from January 2018 to December 2019. Antihypertensive drugs related to “4+7” policy were selected as study samples, including 7 antihypertensive drugs in the “4+7” List and 17 antihypertensive drugs that have an alternative relationship with the “4+7” List drugs in clinical use. Purchase volume, expenditures, and daily costs were selected as outcome variables, and were measured using Defined Daily Doses (DDDs), Chinese Yuan (CNY), and Defined Daily Drug cost (DDDc), respectively. Segmented linear regression analysis was employed to examine the change of outcome variables before and after the policy intervention. Results: As of December 31, 2019, the completion rate of the agreed purchase volume of the 7 bid-winning antihypertensive drugs reached 173.42% in Shenzhen. After “4+7” policy, the DDDc of bid-winning antihypertensive drugs significantly decreased by 63.79% (-1.30 CNY, 95% CI= -1.43 to -1.18, p<0.001), while the DDDc of non-winning (0.28 CNY, 95% CI= 0.11 to 0.46, p<0.01) and alternative (0.14 CNY, 95% CI= 0.03 to 0.25, p<0.05) antihypertensive drugs increased markedly. The volume of bid-winning antihypertensive drugs significantly increased by 1311.76% (3.12 million DDD, 95% CI= 2.14 to 4.10, p<0.001). The overall costs of the seven “4+7” List antihypertensive drugs significantly declined by 101.34% (-5.96 million CNY, 95% CI= -7.87 to -4.04, p<0.001) after policy intervention, with an absolute reduction of 36.37 million CNY compared with the pre-“4+7” period. Conclusion: An overall satisfying implementation effect was observed in Shenzhen. A preliminary positive policy effect of price cut and cost-saving was observed in the antihypertensive drug category. However, the DDDc of non-winning and alternative drugs increased after policy intervention, suggesting that the price monitoring and drug use management regarding NCDP policy-related drugs should be strengthened. Keywords: National Centralized Drug Procurement (NCDP); "4+7"; volume-based procurement; antihypertensive drugs; China