Table 4. National campaign: number of chest X-rays and chest with/without abdomen CT scans, May-July compared with April 2012 and 2013a.

		Per day			Per working day
	No. of tests	Tests/organisationb/day	% Change from April	P-value	Tests/organisation/working dayc	% Change from April	P-value
GP-referred chest X-rays
2012
April	144 140	25.6	N/A	—	40.4	N/A	—
May–July	566 045	32.8	+28.3	<0.001	47.9	+18.6	<0.001
2013
April	160 865	32.3	N/A	—	46.1	N/A	—
May–July	404 115	26.7	−17.3	<0.001	38.4	−16.7	<0.001
All chest X-rays
2012
April	606 840	107.6	N/A	—	169.9	N/A	—
May–July	1 993 105	115.4	+7.3	<0.001	168.6	−0.8	<0.001
2013
April	600 385	120.6	N/A	—	172.2	N/A	—
May–July	1 624 980	107.5	−10.8	<0.001	154.5	−10.3	<0.001
GP-referred chest +/− abdomen CT scans
2012
April	2145	0.4	N/A	—	0.6	N/A	—
May–July	8215	0.5	+25.1	<0.001	0.7	+15.7	<0.001
2013
April	2940	0.6	N/A	—	0.8	N/A	—
May–July	8360	0.6	−6.3	0.014	0.8	−5.8	0.025
All chest +/− abdomen CT scans
2012
April	28 650	5.1	N/A	—	8.0	N/A	—
May–July	98 455	5.7	+12.3	<0.001	8.3	+3.8	<0.001
2013
April	31 515	6.3	N/A	—	9.0	N/A	—
May–July	92  580	6.1	−3.2	<0.001	8.8	−2.6	<0.001

Results in bold indicate a statistically significant change compared with April (likelihood ratio test of two counts; P<0.05).

^aData for 2013 are interim data (finalised data were not available at the time of analysis).

^bMostly NHS trusts, but also includes independent organisations too. Numbers of organisations submitting data each period are included in the Supplementary Results.

^cA 5-day working week excluding bank holidays (e.g., excludes Easter, Early May, Spring bank holidays, and Queen's Diamond Jubilee bank holiday). The difference before and after the working days adjustment for 2012 is, in part, due to the large proportion of non-working days in April compared with May–July.