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

Table 1 Baseline data, n

Variable	Total	Non-delirium group (n = 453)	Delirium group (n = 79)	χ2/t	P value
Age, years	78.00 [74.00, 82.00]	77.68 ± 4.84	81.33 ± 4.72	6.313	< 0.001
Gender
Male	359	308	51	0.362	0.548
Female	173	145	28
Fracture type
Femoral neck fracture	312	267	45	0.109	0.742
Femoral intertrochanteric fracture	220	186	34
Body mass index, kg/m2	23.44 ± 2.30	23.36 ± 2.17	23.94 ± 2.93	1.695	0.093
History of cognitive impairment
With	19	14	5	2.049	0.152
Without	513	439	74
Smoking history
With	224	195	29	1.108	0.292
Without	308	258	50
Preoperative comorbidities
With	317	267	50	0.529	0.467
Without	215	186	29
Number of comorbidities
≥ 2	473	408	65	4.138	0.042
< 2	59	45	14
Hypertension
With	222	186	36	0.563	0.453
Without	310	267	43
Diabetes
With	73	63	10	0.089	0.766
Without	459	390	69
COPD
With	51	45	6	0.056	0.812
Without	481	408	73
Walking ability before injury
Normal	372	322	50	2.446	0.294
Mild limitation	85	68	17
Inability to walk	75	63	12
ASA grading
1-2	381	335	46	8.182	0.004
3-4	151	118	33

COPD: Chronic obstructive pulmonary disease; ASA: American Society of Anesthesiologists.

Table 2 Laboratory indexes and perioperative indicators

Variable	Total	Non-delirium group (n = 453)	Delirium group (n = 79)	Z/χ2/t	P value
Preoperative RBC count, × 109/L	3.78 ± 0.45	3.81 ± 0.44	3.59 ± 0.50	-3.614	< 0.001
Preoperative WBC, × 109/L	8.21 ± 1.73	8.21 ± 1.74	8.23 ± 1.72	0.108	0.914
Preoperative albumin, g/L	36.00 [33.00, 38.00]	36.00 [34.00, 38.00]	34.00 [31.00, 36.00]	-5.158	< 0.001
Preoperative serum creatinine, μmol/L	66.53 ± 10.68	66.38 ± 10.64	67.40 ± 10.95	0.772	0.442
Preoperative hemoglobin, g/L	115.90 ± 12.88	116.81 ± 13.17	110.71 ± 9.65	-4.883	< 0.001
Preoperative PLT, × 109/L	173.96 ± 34.33	176.61 ± 33.22	158.73 ± 36.79	-4.041	< 0.001
Time from admission to surgery, days	6.00 [5.00, 6.00]	6.00 [5.00, 6.00]	6.00 [5.00, 7.00]	1.533	0.11
Mode of anesthesia
Intravertebral/nerve block/local anesthesia	443	381	62	1.528	0.216
General anesthesia	89	72	17
Operation time, minutes	137.00 [123.00, 160.00]	137.00 [123.00, 160.00]	137.00 [126.00, 158.00]	0.296	0.767
Intraoperative blood loss, mL	200.00 [100.00, 300.00]	200.00 [100.00, 300.00]	300.00 [200.00, 300.00]	3.238	< 0.001
RBC transfusion ≥ 2 units
With	255	204	51	10.274	0.001
Without	277	249	28
Postoperative ICU care
With	88	63	25	15.332	< 0.001
Without	444	390	54

RBC: Red blood cell; WBC: White blood cell; PLT: Platelet count; ICU: Intensive care unit.

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.

Table 4 Receiver operating characteristic curve parameters of 7 characteristic factors

Marker	AUC	95%CI	Specificity	Sensitivity	Youden index	Cut off
Age	0.705	0.629-0.781	65.20%	66.04%	31.24%	79.5
History of cognitive impairment	0.525	0.488-0.562	97.49%	7.55%	5.04%	0.5
Preoperative RBC count	0.63	0.544-0.717	57.68%	67.92%	25.60%	3.725
Preoperative albumin	0.7	0.621-0.779	75.24%	54.72%	29.95%	33.5
Preoperative hemoglobin	0.645	0.574-0.717	36.36%	88.68%	25.04%	121.5
Preoperative PLT	0.605	0.518-0.693	83.07%	39.62%	22.69%	145.5
Intraoperative blood loss	0.598	0.519-0.677	65.52%	49.06%	14.57%	250

AUC: Area under the curve; CI: Confidence interval; RBC: Red blood cell; PLT: Platelet count.