Table 1.

Estimates from interrupted time-series models of changes in total volume and average treatment cost for all versions of three antineoplastic medications following generic market entry (baseline trend, postentry level and trend changes, and absolute changes at the end of observation period)

	Total volume (DD)		Average cost (¥)
	β	95% CI	P values	β	95% CI	P values
All products of capecitabine
Baseline level	73 847.2	62 503.6 to 85 190.8	<0.001	589.5	582.8 to 596.3	<0.001
Baseline trend	1752.5	1207.1 to 2297.9	<0.001	−1.0	−1.3 to −0.7	<0.001
Level change	−1927.4	−18 519.0 to 14 664.2	0.82	3.7	−6.0 to 13.4	0.44
Trend change	815.0	−66.5 to 1696.5	0.07	−3.1	−3.6 to −2.6	<0.001
Total change by end of observation	32 260.9	−6366.3 to 70 888.0	0.10	−130.3	−142.6 to −118.0	<0.001
All products of decitabine
Baseline level	85.2	−8.6 to 179.1	0.07	10 154.4	9888.8 to 10 420.0	<0.001
Baseline trend	8.8	2.0 to 15.6	0.01	−3.3	−22.0 to 15.3	0.72
Level change	−30.2	−142.0 to 81.6	0.59	266.4	−37.3 to 570.2	0.08
Trend change	11.0	3.7 to 18.3	0.004	−84.7	−104.7 to −64.6	<0.001
Total change by end of observation	437.7	193.6 to 681.7	<0.001	−3266.4	−3459.9 to −3073.0	<0.001
All products of imatinib
Baseline level	10 903.9	5883.6 to 15 924.2	<0.001	1185.7	1143.9 to 1227.5	<0.001
Baseline trend	817.8	544.7 to 1090.9	<0.001	−0.1	−2.3 to 2.1	0.90
Level change	−6343.7	−13 187.1 to 499.6	0.07	−43.1	−98.2 to 12.0	0.12
Trend change	2145.5	1784.1 to 2506.9	<0.001	−21.3	−24.2 to −18.4	<0.001
Total change by end of observation	82 559.3	61 461.9 to 103 656.9	<0.001	−986.1	−1055.8 to −916.3	<0.001

DD, daily dose.