Effects of Regulation on Carbapenem Prescription in a Large Teaching Hospital in China: An Interrupted Time Series Analysis, 2016–2018

Figures & data

Table 1 Characteristics of Inpatients During the Pre- and Post-Intervention Periods

Characteristic	Pre-Intervention	Post-Intervention	p-value
Admissions, n	1054	951
Age, mean	61.99	60.76	0.27^a
Male	645 (61.2)	571 (54.2)	0.087
Principal diagnosis (top 5), n (%^b)			0.28
Chronic obstructive pneumonia	143 (13.6)	97 (9.2)
Pneumonia	59 (5.6)	61 (5.8)
Pulmonary infections	48 (4.6)	49 (4.6)
Sepsis	40 (3.8)	50 (4.7)
Infectious fever	21 (2.0)	26 (2.5)
Main departments			0.13
Intensive care unit	311 (29.5)	330 (31.3)
Respiratory medicine	200 (19)	111 (10.6)
Paediatrics	96 (9.1)	95 (9.0)
Haematology	83 (7.9)	61 (5.8)

Notes: Data are number (%) unless otherwise indicated. All p-values were calculated using the Chi-square test unless otherwise noted. ^at-test; ^bThe percentage of patients with the indicated diagnosis who received antibiotics as a percentage of the total patients in the same period.

Abbreviation: SD, standard deviation.

Figure 1 The change in the IAC of carbapenems per month pre- and post-intervention in all departments.

Figure 2 The change in the IAC of carbapenems per month pre- and post-intervention in the ICU.

Figure 3 The change in the ALoS per month pre- and post-intervention.

Table 2 Results of the Segmented Regression Analysis of IAC, Cumulative DDDs and ALoS

Outcomes	Coefficient	Standard Error	t- Statistic	p-value
IAC of Carbapenems (all departments) (DW = 2.10)
Baseline level	1.04	0.09	11.17	<0.001
Baseline trend	0.01	0.01	0.44	0.664
Level change after intervention	−0.02	0.12	−0.19	0.850
Trend change after intervention	−0.01	0.01	−0.98	0.334
IAC of Meropenem (all departments) (DW = 1.94)
Baseline level	0.36	0.10	3.71	0.001
Baseline trend	0.01	0.01	1.01	0.319
Level change after intervention	0.06	0.12	0.46	0.647
Trend change after intervention	−0.03	0.01	−2.84	0.008
IAC of Imipenem (all departments) (DW = 2.06)
Baseline level	0.69	0.07	9.31	<0.001
Baseline trend	0.01	0.01	−0.60	0.553
Level change after intervention	−0.10	0.09	−1.08	0.291
Trend change after intervention	0.02	0.01	2.49	0.019
Cumulative DDDs (all departments) (DW = 2.02)
Baseline level	517.37	41.27	12.54	<0.001
Baseline trend	4.38	3.75	1.17	0.252
Level change after intervention	−94.14	51.05	−1.84	0.075
Trend change after intervention	−8.54	4.82	−1.77	0.087
ALoS (all departments) (DW = 1.83)
Baseline level	9.79	0.32	30.39	<0.001
Baseline trend	−0.03	0.03	−0.89	0.382
Level change after intervention	−0.69	0.39	−1.76	0.088
Trend change after intervention	−0.02	0.04	−0.60	0.551
IAC of Carbapenems (ICU) (DW = 1.98)
Baseline level	14.74	1.37	10.78	<0.001
Baseline trend	0.50	0.13	3.99	<0.001
Level change after intervention	−9.65	1.69	−5.72	<0.001
Trend change after intervention	−0.36	0.16	−2.21	0.035
IAC of Meropenem (ICU) (DW = 1.84)
Baseline level	6.21	1.91	3.25	0.003
Baseline trend	0.11	0.18	0.61	0.547
Level change after intervention	−3.22	2.34	−1.38	0.179
Trend change after intervention	0.12	0.23	0.54	0.597
IAC of Imipenem (ICU) (DW = 1.85)
Baseline level	8.55	1.68	5.08	<0.001
Baseline trend	0.41	0.16	2.64	0.013
Level change after intervention	−6.82	2.05	−3.34	0.002
Trend change after intervention	−0.49	0.21	−2.37	0.025
Cumulative DDDs (ICU) (DW = 1.97)
Baseline level	138.24	34.39	4.02	<0.001
Baseline trend	10.33	3.18	3.25	0.003
Level change after intervention	−133.60	40.85	−3.27	0.003
Trend change after intervention	−7.62	4.30	−1.77	0.087
ALoS (ICU) (DW = 2.01)
Baseline level	16.13	1.06	15.26	<0.001
Baseline trend	0.21	0.10	2.24	0.033
Level change after intervention	2.30	1.31	1.76	0.089
Trend change after intervention	−0.73	0.12	−6.03	<0.001

Notes: DW, Durbin-Watson coefficient; bold text, regression results are significant after intervention.

Abbreviations: ITS, interrupted time series; IFCP, Information Form of Carbapenem Prescription; IAC, intensity of antibiotic consumption; ALoS, average length of stay; DDDs, cumulative defined daily dose.