Table 3

Descriptive characteristics of study population and distribution of appropriateness of diagnostic examination (CT/MRI) according to various explanatory variables

Characteristic	Patients who received at least one CT		Appropriate CT examinations		Patients who received at least one MRI		Appropriate MRI examinations
Characteristic	n	%	n	%	n	%	n	%
Overall	639*	74.9	496*	77.6	256*	30	202*	78.9
Age (years)
<46	69	10.80	58	84.06	101	39.45	75	74.26
46–55	65	10.17	50	76.92	51	19.92	41	80.39
56–65	110	17.21	83	75.45	49	19.14	41	83.67
66–75	146	22.85	111	76.03	38	14.84	30	78.95
>75	249	38.97	194	77.91	17	6.64	15	88.24
			χ²=2.18, 4 df, P=0.701				Fisher’s exact test: P=0.634
Previous hospitalisations
No	427	67.89	334	78.22	131	52.19	102	77.86
Yes	202	32.11	156	77.23	120	47.81	95	79.17
			χ²=0.08, 1 df, P=0.779				χ²=0.06, 1 df, P=0.802
Charlson Comorbidity Index
0	260	42.41	201	77.3	174	69.32	137	78.74
≥1	353	57.59	277	78.5	77	30.68	60	77.92
			χ²=0.12, 1 df, P=0.731				χ²=0.021, 1 df, P=0.885
Length of stay, days, mean (SD)	11.62 (8.24)				11.04 (7.04)
Appropriate group			11.2 (9.0)				10.8 (7.2)
Inappropriate group			12.9 (9.9)				11.9 (6.4)
			T=−1.98, 637 df, P=0.047				T=−1.01, 254 df, P=0.31
Admission type
Urgent	404	63.62	327	80.94	51	20.4	44	86.27
Planned	231	36.38	167	72.29	199	79.6	154	77.39
			χ²=6.36, 1 df, P=0.012				Fisher’s exact test: P=0.181
Admission ward
Medical	425	66.51	329	77.41	237	92.58	187	78.90
Surgical	214	33.49	167	78.04	19	7.42	15	78.95
			χ²= 0.03, 1 df, P=0.858				Fisher’s exact test: P=1.000
Previous outpatient CT/MRI examinations
No	474	76.82	366	77.22	140	55.12	112	80
Yes	143	23.18	116	81.12	114	44.88	88	77.19
			χ²=0.98, 1 df, P=0.322				χ²=0.29, 1 df, P=0.587
Contrast agent use
No	388	60.72	337	86.86	146	57.03	112	76.71
Yes	251	39.28	159	63.35	110	42.97	90	81.82
			χ²=48.49, 1 df, P<0.001				χ²=0.98, 1 df, P=0.322
Diagnostic confirmation of the clinical hypothesis
No	105	16.43	45	42.86	33	12.89	20	60.61
Yes	534	87.57	451	84.46	223	87.11	182	81.61
			χ²=87.41, 1 df, P<0.001				χ²=7.62, 1 df, P=0.006
Anatomical scan region
Abdomen/pelvis	148	24.07	118	79.73	34	14.11	32	94.12
Chest	140	22.76	112	80	1	0.41	1	100
Head	218	35.45	173	79.36	164	68.05	143	87.20
Whole body	64	10.41	40	62.5	–	–	–	–
Musculoskeletal system/spine/extremities	13	2.11	8	61.54	28	11.62	13	46.43
Vascular system	32	5.20	27	84.38	14	5.81	0	0
			Fisher’s exact test: P=0.038				Fisher’s exact test: P<0.001
More than one examination performed during hospital stay
No	540	84.51	439	81.30	164	64.06	148	90.24
Yes	99	15.49	57.58	57.58	92	35.94	54	58.70
			χ²=27.09, 1 df, P<0.001				χ²=35.24, 1 df, P<0.001

*Total may not always sum to n because of missing data.