Postoperative delirium after major orthopedic surgery

Table 4 Total knee arthroplasty patient demographics and study population

	POD (Mean +/- SD or n, %), n = 245	non-POD (Mean +/- SD or n, %), n = 19864	P value
Age, yr	75.1+/-9.3	67.6+/-10	< 0.001a
≥ 70	171 (69.8)	8304 (41.8)	< 0.001a
Male	89 (36.3)	7364 (37.1)	0.81
BMI	30.0+/-6.1	30.6+/-6.3	0.13
Length of stay	6.0+/-3.2	3.8+/-1.5	< 0.001a
Latest creatinine before surgery			< 0.001a
< 1.2 mg/dL	203 (82.9)	17828 (89.8)
1.2-2.0 mg/dL	37 (15.1)	1954 (9.8)
> 2.0 mg/dL	5 (2.0)	82 (0.4)
Preoperative hyponatremia			0.07
Yes	45 (18.4)	2837 (14.3)
No	200 (81.6)	17019 (85.7)
Missing	0 (0)	8 (0.04)
Postoperative thiamine order			< 0.001a
Yes	28 (11.4)	332 (1.7)
No	217 (88.6)	19530 (98.3)
Missing	0 (0)	2 (0.01)
Atrial fibrillation (present on admission)	46 (18.8)	1190 (6.0)	< 0.001a
Pressure ulcers (present on admission)	1 (0.4)	29 (0.2)	0.31
Opioid dependence or long-term use	9 (3.7)	198 (1.0)	0.001a
Psychiatric disease (present on admission)	77 (31.4)	3915 (19.7)	< 0.001a
Anesthesia type			0.04a
General	12 (4.9)	545 (2.7)
Other	233 (95.1)	19252 (96.9)
Missing	0 (0)	67 (0.3)
Patient-controlled analgesia			0.005a
Epidural	179 (73.1)	15151 (76.3)
IV	38 (15.5)	1801 (9.1)
Peripheral nerve infusion	9 (3.7)	711 (3.6)
Missing	19 (7.8)	2201 (11.1)
Received diazepam			0.003a
Yes	12 (4.9)	381 (1.9)
No	233 (95.1)	19481 (98.1)
Missing	0 (0)	2 (0.01)
CT, MRI or both performed			0.14
Yes	226 (92.2)	17733 (89.3)
No	19 (7.8)	2129 (10.7)
Missing	0 (0)	2 (0.01)
ASA score			< 0.001a
1	2 (0.8)	489 (2.46)
2	130 (53.1)	14933 (75.2)
≥ 3	113 (46.1)	4327 (22.0)
Missing	0 (0)	70 (0.4)

^aP value < 0.05. POD: Postoperative delirium; ASA: American society of anesthesiologists; CT: Computed tomography; MRI: Magnetic resonance imaging; BMI: Body mass index; SD: Standard deviation.