Table 3.

Incidence rate-ratios for an interrupted time-series model of antibiotic prescriptions

Parameter	Co-efficient	Incidence rate ratio (95 % confidence interval)	P-value
		Antibiotic starts, UTI
Pre-intervention trend	β1	1.04 (1.00–1.07)	0.06
Immediate intervention change	β2	0.74 (0.64–0.84)	<0.001
Change in trend after intervention	β3	0.91 (0.89–0.93)	<0.001
Intervention trend	β1 + β3	0.94 (0.92–0.97)	<0.001
		All antibiotic starts
Pre-intervention trend	β1	1.04 (0.96–1.13)	0.30
Immediate intervention change	β2	0.75 (0.67–0.84)	<0.001
Change in trend after intervention	β3	0.91 (0.81–1.02)	0.09
Intervention trend	β1 + β3	0.95 (0.92–0.98)	0.001