Table 2.

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

	Volume (DD)			Cost (¥)
	β	95% CI	P values	β	95% CI	P values
Brand-name capecitabine
Baseline level	73 849.7	63 800.4 to 83 899.1	<0.001	590.3	581.6 to 599.0	<0.001
Baseline trend	1752.5	1269.2 to 2235.7	<0.001	−1.0	−1.4 to −0.6	<0.001
Level change	2333.7	−12 366.5 to 17 034.0	0.75	5.4	−6.6 to 17.4	0.37
Trend change	−2425.8	−3206.8 to −1644.8	<0.001	0.6	−0.1 to 1.2	0.054
Total change by end of observation	−99 342.2	−133 858.0 to −64 826.9	<0.001	28.8	19.9 to 37.6	<0.001
Brand-name decitabine
Baseline level	92.2	31.0 to 153.5	0.004	10150.7	10 119.4 to 10 182.0	<0.001
Baseline trend	8.5	4.0 to 12.9	<0.001	−3.1	−5.4 to −0.8	0.008
Level change	63.4	−12.4 to 139.1	0.10	10.3	−26.8 to 47.4	0.58
Trend change	−8.3	−13.1 to −3.4	<0.001	2.6	0.2 to 5.1	0.04
Total change by end of observation	−283.8	−497.3 to −70.2	0.009	124.6	9.5 to 239.8	0.03
Brand-name imatinib
Baseline level	11 171.1	6806.0 to 15 536.3	<0.001	1190.6	1139.6 to 1241.6	<0.001
Baseline trend	815.1	577.0 to 1053.3	<0.001	−0.4	−3.0 to 2.3	0.79
Level change	8278.3	2396.6 to 14 160.1	0.007	−41.7	−107.6 to 24.2	0.21
Trend change	−706.9	−1022.7 to −391.2	<0.001	−0.3	−3.8 to 3.2	0.87
Total change by end of observation	−22 227.6	−37 807.7 to −6647.4	0.005	−109.7	−168.0 to −51.4	<0.001

DD, daily dose.