Effects of automated alerts on unnecessarily repeated serology tests in a cardiovascular surgery department: a time series analysis

Table 1 Characteristics of patients and hospital stays with at least one HBs antigen test in the Cardiovascular Surgery department during the study period.

Period*†	Pre-intervention	Intervention period
Characteristics	period	Adjustment period	Effective intervention period
Patients‡	(n = 2888)	(n = 455)	(n = 1072)
Male, n (%)	2044 (70.8)	321 (70.5)	767 (71.5)
Age (years), median (IQR)	64 (53 to 74)	64 (54 to 74)	65 (55 to 74)
Hospital stays§	(n = 3412)	(n = 605)	(n = 1395)
With transplant, n (%)	34 (1.0)	16 (2.6)	35 (2.5)
Length of stays (days), median (IQR)	10 (4 to 15)	10 (4 to 15)	10 (5 to 16)

IQR = Interquartile Range
* We identified patients and hospital stays for a period according to the first HBs antigen test in the Cardiovascular Surgery department.
† Pre-intervention period: January 2004 to May 2006, Adjustment period: July 2006 to November 2006; Effective intervention period: December 2006 to December 2007. June 2006 is not presented: it has been excluded from analysis since the intervention was initiated mid-month. 117 patients (157 hospital stays) had a first HBs antigen test in the Cardiovascular Surgery department during June 2006.
‡ The two segmented regression models predicting monthly proportion of males and median age of patients indicated there were no level and trend changes for age and sex ratio during the study period (time series data not shown).
§ The two segmented regression models predicting monthly proportion of stays with transplant and median length of stays indicated respectively an increase of stays with transplant during the pre-intervention period and a significant decrease of length of stays during the effective intervention period (trend change) (time series data not shown).

ISSN: 1472-6963