Developing a nomogram for postoperative delirium in elderly patients with hip fractures

Table 3 Comparison of baseline features and preoperative and intraoperative indicators between the training and validation groups

Variable	Total	Training group (n = 372)	Validation group (n = 160)	Z/χ2/t	P value
Delirium status
With	79	53	26	0.355	0.551
Without	453	319	134
Gender
Male	359	259	100	2.587	0.108
Female	173	113	60
Fracture type
Femoral neck fracture	312	216	96	0.173	0.678
Femoral intertrochanteric fracture	220	156	64
History of cognitive impairment
With	19	12	7	0.429	0.512
Without	513	360	153
Smoking history
With	224	160	64	0.416	0.519
Without	308	212	96
Preoperative comorbidities
With	317	219	98	0.263	0.608
Without	215	153	62
Number of comorbidities
≥ 2	59	40	19	0.143	0.705
< 2	473	332	141
Hypertension
With	222	152	70	0.384	0.535
Without	310	220	90
Diabetes
With	73	51	22	< 0.001	0.990
Without	459	321	138
COPD
With	51	35	16	0.045	0.832
Without	481	337	144
Walking ability before injury
Normal	75	57	18	5.307	0.07
Mild limitation	85	66	19
Inability to walk	372	249	123
ASA grading
1-2	381	264	117	0.256	0.613
3-4	151	108	43
Mode of anesthesia
Intravertebral/nerve block/local anesthesia	443	307	136	0.491	0.483
General anesthesia	89	65	24
RBC transfusion ≥ 2 units
With	255	181	74	0.259	0.61
Without	277	191	86
Postoperative ICU care
With	88	60	28	0.152	0.696
Without	444	312	132
Age, years	78.00 [74.00, 82.00]	78.00 [74.00, 82.00]	78.34 ± 4.51	0.585	0.558
Body mass index, kg/m2	23.44 ± 2.30	23.47 ± 2.28	23.37 ± 2.36	-0.483	0.629
Preoperative RBC count, × 109/L	3.78 ± 0.45	3.78 ± 0.46	3.77 ± 0.45	-0.255	0.799
Preoperative WBC, × 109/L	8.21 ± 1.73	8.13 ± 1.73	8.41 ± 1.73	1.714	0.088
Preoperative albumin, g/L	36.00 [33.00, 38.00]	36.00 [33.00, 38.00]	35.89 ± 3.99	0.89	0.372
Preoperative serum creatinine, μmol/L	66.53 ± 10.68	66.41 ± 10.76	66.82 ± 10.52	0.412	0.681
Preoperative hemoglobin, g/L	115.90 ± 12.88	115.97 ± 12.66	115.76 ± 13.44	-0.162	0.871
Preoperative PLT, × 109/L	173.96 ± 34.33	174.88 ± 33.84	171.81 ± 35.46	-0.927	0.355
Time from admission to surgery, days	6.00 [5.00, 6.00]	6.00 [5.00, 6.00]	6.00 [5.00, 6.00]	0.214	0.824
Operation time, minutes	137.00 [123.00, 160.00]	137.00 [123.00, 157.00]	139.00 [123.75, 164.25]	1.044	0.296
Intraoperative blood loss, mL	200.00 [100.00, 300.00]	200.00 [100.00, 300.00]	200.00 [100.00, 300.00]	-0.169	0.86

COPD: Chronic obstructive pulmonary disease; ASA: American Society of Anesthesiologists; RBC: Red blood cell; ICU: Intensive care unit; WBC: White blood cell count; PLT: Platelet count.