Table 3

Month-on-month absolute percentage changes (with 95% CIs) in antibiotic use before and after the publication of CG149 and NG195

OutcomeJanuary 2010–July 2012
(period 1; pre-CG149)		August 2012–March 2021
(period 2; postpublication of CG149)		April 2021–December 2022
(period 3; postpublication of NG195)		Magnitude at start and end of study period (%) and reduction in number of days/infants with outcome per month*
Trend pre-CG149Immediate change in level compared with pre-CG149Change in trend compared with pre-CG149Absolute trend August 2012–March 2021Immediate change in level compared with August 2012–March 2021Change in trend compared with August 2012–March 2021Absolute trend April 2021–December 2022
Antibiotic use rate0.03
(0.00 to 0.06)		−1.02
(−1.57 to –0.47)		−0.05
(−0.08 to –0.03)		−0.02
(−0.03 to –0.02)		n/an/a−0.02
(−0.03 to –0.02)		20.5, 17.5;
1000 fewer days per month
Received ≥1 day of antibiotics for EOIn/an/an/an/an/a−0.20
(−0.26 to –0.14)		−0.20
(−0.26 to –0.14)		93.6, 89.5;
22 fewer infants per month
Received ≥1 day of antibiotics for LOI0.02
(0.01 to 0.03)		n/an/a0.02
(0.01 to 0.03)		n/a−0.25
(−0.36 to –0.14)		−0.23
(−0.33 to –0.12)		52.9, 50.7;
12 fewer infants per month
Received ≥1 prolonged course of antibiotics for EOIn/a−1.87
(−2.97 to –0.78)		−0.08
(−0.09 to –0.07)		−0.08
(−0.09 to –0.07)		n/an/a−0.08
(−0.09 to –0.07)		41.3, 29.1;
66 fewer infants per month
Received ≥1 prolonged course of antibiotics for LOI0.12
(0.04 to 0.21)		−2.85
(−0.54 to –0.15)		−0.14
(−0.23 to –0.06)		−0.02
(−0.03 to –0.01)		n/a−0.12
(−0.22 to –0.03)		−0.14
(−0.24 to –0.05)		33.0, 28.7;
23 fewer infants per month

  • n/a, variable not included in parsimonious model.

  • *Magnitude of effect calculated assuming a constant population size and expressed as the reduction in the number of days/infants with antibiotics in the last month of the study period compared with the first month.

  • CG149, clinical guideline 149; NG195, NICE guideline 195.