Table. Results of Interrupted Time Series Analyses of the Impact of Government Price Regulation on Daily Cost, Volume and Spending for Price-Regulated and Price-Unregulated Antibiotics, 2011-2015 .

	Baseline Level	Baseline Trend	Post-regulation Level Change	Post-regulation Trend Change	Change at 12 Months After Regulation
Average daily cost (USD)
Price-regulated group	39.90***	-0.09***	-5.68***	NS	-5.56***
Price-unregulated group	17.78***	-0.04***	NS	NS	NS
Difference	22.05**	NS	-5.67***	NS	-5.41***
Average hospital purchasing volume (Thousand DDD)
Price-regulated group	274.84***	4.65***	NS	NS	NS
Price-unregulated group	172.22***	-1.78**	NS	2.94**	45.22*
Difference	99.80***	6.65***	-37.13*	-3.09**	-74.21***
Average hospital purchase spending (million USD)
Price-regulated group	2.11***	0.04***	-0.49**	NS	-0.73**
Price-unregulated group	1.81***	-0.03***	NS	0.04***	0.58**
Difference	0.28*	0.07***	-0.61***	-0.06***	-1.35***

Abbreviations: DDD, defined daily dose; NS, not significant.

* P < .050; ** P < .010; *** P < .001;

Price-regulated group: 11 antibiotics with price regulation in 2013.

Price-unregulated group: 40 antibiotics without price regulation.