Association of preoperative depression and cognitive status with postoperative delirium in elderly patients with hip fracture

Table 1 Baseline characteristics and comparison between patients with and without postoperative delirium, n (%)/mean ± SD/median (interquartile range)

Characteristic	Total (n = 150)	No POD (n = 104)	POD (n = 46)	P value
Demographics
Age (years)	78.4 ± 7.8	77.1 ± 7.7	81.2 ± 7.4	0.003
Age ≥ 80 years	61 (40.7)	36 (34.6)	25 (54.3)	0.024
Female sex	102 (68.0)	72 (69.2)	30 (65.2)	0.635
Body mass index (kg/m2)	22.8 ± 3.6	23.1 ± 3.5	22.1 ± 3.8	0.128
Education ≥ 6 years	89 (59.3)	64 (61.5)	25 (54.3)	0.413
Living alone	34 (22.7)	22 (21.2)	12 (26.1)	0.508
Current smoker	28 (18.7)	18 (17.3)	10 (21.7)	0.527
Fracture characteristics
Fracture type				0.624
Femoral neck	57 (38.0)	41 (39.4)	16 (34.8)
Intertrochanteric	86 (57.3)	58 (55.8)	28 (60.9)
Subtrochanteric	7 (4.7)	5 (4.8)	2 (4.3)
Fall as mechanism	134 (89.3)	92 (88.5)	42 (91.3)	0.604
Time to surgery (days)	3 (2, 5)	3 (2, 4)	3 (2, 5)	0.267
Comorbidities
Hypertension	98 (65.3)	66 (63.5)	32 (69.6)	0.477
Diabetes mellitus	42 (28.0)	27 (26.0)	15 (32.6)	0.409
Coronary artery disease	35 (23.3)	22 (21.2)	13 (28.3)	0.349
Chronic obstructive pulmonary disease	18 (12.0)	11 (10.6)	7 (15.2)	0.424
Cerebrovascular disease	22 (14.7)	13 (12.5)	9 (19.6)	0.263
Chronic kidney disease	15 (10.0)	8 (7.7)	7 (15.2)	0.154
Number of comorbidities ≥ 3	56 (37.3)	35 (33.7)	21 (45.7)	0.163
American Society of Anesthesiologists classification ≥ III	72 (48.0)	42 (40.4)	30 (65.2)	0.006
Preoperative assessments
GDS-15 score	4.2 ± 3.1	3.6 ± 2.8	5.6 ± 3.4	< 0.001
Depression (GDS-15 ≥ 5)	58 (38.7)	33 (31.7)	25 (54.3)	0.012
Mild depression (GDS-15: 5-8)	43 (28.7)	27 (26.0)	16 (34.8)
Moderate depression (GDS-15: 9-11)	12 (8.0)	5 (4.8)	7 (15.2)
Severe depression (GDS-15 ≥ 12)	3 (2.0)	1 (1.0)	2 (4.3)
MMSE score	24.8 ± 4.6	25.9 ± 3.8	22.4 ± 5.4	< 0.001
Cognitive impairment (MMSE < 24)	50 (33.3)	24 (23.1)	26 (56.5)	< 0.001
Activities of Daily Living score	82.4 ± 16.8	84.6 ± 15.2	77.2 ± 19.1	0.015
Preoperative laboratory values
Hemoglobin (g/L)	108.2 ± 17.6	110.5 ± 16.2	103.2 ± 18.6	0.021
< 100 g/L	38 (25.3)	21 (20.2)	17 (37.0)	0.032
Albumin (g/L)	36.0 ± 4.6	36.8 ± 4.2	34.2 ± 4.8	0.002
Albumin < 35 g/L	52 (34.7)	29 (27.9)	23 (50.0)	0.009
Creatinine (μmol/L)	78 (65, 95)	76 (64, 92)	82 (68, 98)	0.142
Surgical characteristics
Surgical procedure				0.482
Internal fixation	87 (58.0)	62 (59.6)	25 (54.3)
Hemiarthroplasty	46 (30.7)	30 (28.8)	16 (34.8)
Total hip arthroplasty	17 (11.3)	12 (11.5)	5 (10.9)
Anesthesia type				0.584
General	84 (56.0)	57 (54.8)	27 (58.7)
Regional	66 (44.0)	47 (45.2)	19 (41.3)
Surgical duration (minutes)	117.8 ± 35.2	112.3 ± 32.6	128.6 ± 38.4	0.008
> 120 minutes	58 (38.7)	34 (32.7)	24 (52.2)	0.026
Blood loss (mL)	300 (200, 450)	300 (200, 400)	350 (200, 500)	0.186
Intraoperative transfusion	51 (34.0)	30 (28.8)	21 (45.7)	0.048

GDS-15: 15-item Geriatric Depression Scale; MMSE: Mini-Mental State Examination; POD: Postoperative delirium.

Table 2 Incidence of postoperative delirium according to preoperative depression and cognitive status, n (%)

Variable	n	POD	No POD	P value
Preoperative depression (GDS-15)
No depression (GDS-15 < 5)	92	20 (21.7)	72 (78.3)	0.003
Depression (GDS-15 ≥ 5)	58	26 (44.8)	32 (55.2)
Preoperative Cognitive Status (MMSE)
Normal cognition (MMSE ≥ 24)	100	19 (19.0)	81 (81.0)	< 0.001
Cognitive impairment (MMSE < 24)	50	27 (54.0)	23 (46.0)
Combined categories
Neither depression nor cognitive impairment	64	9 (14.1)	55 (85.9)	< 0.001
Depression only (no cognitive impairment)	36	13 (36.1)	23 (63.9)
Cognitive impairment only (no depression)	28	11 (39.3)	17 (60.7)
Both depression and cognitive impairment	22	13 (59.1)	9 (40.9)

GDS-15: 15-item Geriatric Depression Scale; MMSE: Mini-Mental State Examination; POD: Postoperative delirium.

Table 3 Univariate logistic regression analysis for risk factors of postoperative delirium

Variable	Odds ratio	95%CI	P value
Age ≥ 80 years	2.68	1.32-5.44	0.006
Female sex	0.84	0.40-1.76	0.635
Body mass index < 18.5 kg/m2	1.86	0.74-4.67	0.189
Education < 6 years	1.34	0.66-2.72	0.414
Living alone	1.32	0.59-2.95	0.509
American Society of Anesthesiologists classification ≥ III	2.77	1.38-5.58	0.004
Preoperative depression (15-item Geriatric Depression Scale ≥ 5)	2.64	1.28-5.44	0.008
Preoperative cognitive impairment (Mini-Mental State Examination < 24)	4.67	2.25-9.70	< 0.001
Activities of Daily Living score (per 10-point decrease)	1.28	1.04-1.58	0.021
Number of comorbidities ≥ 3	1.65	0.82-3.31	0.164
Hypertension	1.31	0.62-2.75	0.477
Diabetes mellitus	1.37	0.65-2.90	0.410
Coronary artery disease	1.47	0.66-3.26	0.350
Hemoglobin < 100 g/L	2.18	1.06-4.49	0.035
Albumin < 35 g/L	2.92	1.44-5.93	0.003
Intertrochanteric fracture (vs femoral neck)	1.23	0.60-2.54	0.574
Time to surgery > 3 days	1.54	0.77-3.08	0.222
General anesthesia (vs regional)	1.17	0.58-2.37	0.659
Surgical duration > 120 minutes	2.34	1.16-4.71	0.017
Intraoperative blood transfusion	2.09	1.01-4.31	0.046

Table 4 Multivariable logistic regression analysis for independent predictors of postoperative delirium

Variable	Adjusted odds ratio	95%CI	P value
Preoperative depression (15-item Geriatric Depression Scale ≥ 5)	2.84	1.26-6.41	0.012
Preoperative cognitive impairment (Mini-Mental State Examination < 24)	3.92	1.71-8.98	0.001
Age ≥ 80 years	2.47	1.09-5.59	0.030
American Society of Anesthesiologists classification ≥ III	2.63	1.18-5.87	0.018
Albumin < 35 g/L	1.85	0.82-4.18	0.137
Surgical duration > 120 minutes	1.72	0.78-3.80	0.179

Model statistics: (1) Area under the curve = 0.78 (95%CI: 0.71-0.86); and (2) Hosmer-Lemeshow test P = 0.42.

Table 5 Postoperative delirium incidence according to combined depression and cognitive status, n (%)

Depression status	Cognitive status	n	Postoperative delirium	Adjusted odds ratio1	95%CI	P value
No	Normal	64	9 (14.1)	Reference	-	-
Yes	Normal	36	10 (27.8)	2.45	0.89-6.71	0.082
No	Impaired	28	11 (39.3)	3.94	1.42-10.95	0.008
Yes	Impaired	22	16 (72.7)	12.89	4.01-41.49	< 0.001

¹Adjusted for age, sex, American Society of Anesthesiologists classification, preoperative albumin level, and surgical duration.