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

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.