Table 1.

Changes in Antimicrobial Use Before and After the Implementation of Postprescription Review and Feedback Analyzed by Interrupted Time Series Analysis^a

	Days of Therapy per 1000 Patient-Days per Month
Antimicrobials	Baseline Trend in the Preintervention Period (95% CI)	P	Slope in the Intervention Period (95% CI)	P	Change in Slope	P
Carbapenems	−0.73 (−0.89 to −0.57)	<.001	−0.003 (−0.06 to 0.06)	.92	0.73 (0.55–0.91)	<.001
Piperacillin/tazobactam	−0.04 (−0.31 to 0.24)	.80	−0.24 (−0.33 to −0.15)	<.001	−0.20 (−0.49 to 0.08)	.16
Cefepime	0.12 (−0.10 to 0.34)	.29	0.35 (0.18–0.52)	<.001	0.23 (−0.04 to 0.51)	.19
3 antipseudomonal agents	−0.63 (−0.91 to −0.36)	<.001	0.10 (−0.05 to 0.26)	.21	0.73 (0.42–1.06)	<.001
Fluoroquinolones	−0.04 (−0.11 to 0.02)	.21	−0.02 (−0.05 to 0.01)	.07	0.02 (−0.05 to 0.09)	.63
Ceftazidime	−0.05 (−0.12 to 0.14)	.29	−0.06 (−0.10 to −0.02)	.001	−0.01 (−0.08 to 0.06)	.82
Cefazolin	−0.16 (−0.45 to 0.13)	.76	0.03 (−0.11 to 0.17)	.63	0.19 (−0.13 to 0.52)	.24
Ampicillin	0.33 (0.26–0.41)	<.001	0.02 (−0.03 to 0.07)	.54	−0.32 (−0.42 to −0.22)	<.001
Ampicillin/sulbactam	−0.36 (−0.53 to −0.18)	<.001	0.22 (0.08–0.35)	.002	0.58 (0.35–0.80)	<.001
Cefamycins	−0.04 (−0.29 to 2.13)	.76	−0.51 (−0.62 to −0.41)	<.001	−0.47 (−0.75 to −0.20)	<.001
Ceftriaxone	0.59 (0.36–0.82)	<.001	0.37 (0.28–0.47)	<.001	−0.22 (−0.47 to 0.04)	.10
Vancomycin	0.15 (−0.01 to 0.30)	.05	0.09 (−0.01 to 0.18)	.06	−0.06 (−0.24 to 0.12)	.49
All antimicrobials	−0.27 (−0.91 to 0.37)	.40	0.29 (−0.04 to 0.62)	.09	0.56 (−0.18 to 1.30)	.13
Overall antimicrobial cost, $	9.5 (−12.9 to 31.8)	.84	−27.9 (−36.7 to −19.1)	<.001	−37.4 (−61.6 to −13.2)	.003

Abbreviations: CI, confidence interval; USD, US dollar.

^aOverall antimicrobial cost was calculated at the rate of 100 Yen = 1 USD.