High ASA Physical Status and Low Serum Uric Acid to Creatinine Ratio are Independent Risk Factors for Postoperative Delirium Among Older Adults Undergoing Urinary Calculi Surgery

Figures & data

Figure 1 Flow chart of study population.

Figure 2 The distribution characteristics of postoperative delirium.

Notes: (A) Time of the onset of postoperative delirium. (B) The incidence of postoperative delirium in various surgical procedures.

Abbreviations: URSL, Ureteroscopic Lithotripsy; PCNL, Percutaneous Nephrolithotomy; THLC, Transurethral Holmium Laser Cystolithotripsy.

Table 1 Characteristics of Patients with and without Delirium

Variables	Overall (N=195)	Delirium (n=19)	Non-Delirium (n=176)	p-value
Age (years)	68 (66–72)	70 (66–76)	68 (66–71.8)	0.047*
Age ≥70	77 (39.5)	11 (57.9)	66 (37.5)	0.084
Gender (male)	135 (69.2)	12 (63.2)	123 (69.9)	0.546
BMI (kg/m²)	25.7 (24.2–28.1)	24.5 (23.2–27.7)	25.8 (24.2–28.2)	0.173
ASA status, n (%)
1~2	124 (63.6)	7 (36.8)	117 (66.5)	0.011*
3~4	71 (36.4)	12 (63.2)	59 (33.5)
Smoking status, n (%)
No smoking	159 (81.5)	15 (78.9)	144 (81.8)	0.464
Current smoking	28 (14.4)	4 (21.1)	24 (13.6)
Ever smoking	8 (4.1)	0 (0)	8 (4.5)
Drinking history, n (%)
No drinking	168 (86.2)	14 (73.7)	154 (87.5)	0.077
Current drinking	22 (11.3)	5 (26.3)	17 (9.7)
Ever drinking	5 (2.6)	0 (0)	5 (2.8)
Preoperative pain scores	0 (0–0)	0 (0–0)	0 (0–0)	0.909
Preoperative comorbidities, n (%)
Diabetes	54 (27.7)	7 (36.8)	47 (26.7)	0.348
Hypertension	115 (59)	10 (52.6)	105 (59.7)	0.554
Cardiac arrhythmia	25 (12.8)	3 (15.8)	22 (12.5)	0.684
CHD	25 (12.8)	3 (15.8)	22 (12.5)	0.684
Cerebrovascular diseases	30 (15.4)	3 (15.8)	27 (15.3)	0.959
COPD	4 (1.7)	0 (0)	4 (2.3)	0.507
Medical history, n (%)
β-blockers	17 (8.7)	4 (21.1)	13 (7.4)	0.045*
Steroids	14 (7.2)	1 (5.3)	13 (7.4)	0.733
Calcium Channel Blockers	69 (35.4)	5 (26.3)	64 (36.4)	0.384
ACEI	27 (13.8)	1 (5.3)	26 (14.8)	0.254
Diuretics	4 (2.1)	1 (5.3)	3 (1.7)	0.299
Benzodiazepines	3 (1.5)	1 (5.3)	2 (1.1)	0.165
Preoperative laboratory data
White blood cell count (x109/L)	6.2 (5.3–7.2)	6.5 (5.5–8.2)	6.2 (5.3–7.1)	0.280
Neutrophil-to-Lymphocyte Ratio	2.5 (1.9–3.8)	2.4 (1.9–3.8)	2.5 (1.9–3.9)	0.621
Hemoglobin (g/L)	135 (121–146)	129 (120–145)	136 (121.3–146)	0.282
Serum album (g/L)	40.7 (37.9–43.8)	39.6 (37.5–41.4)	40.8 (37.9–43.9)	0.220
Calcium (mmol/L)	2.3 (2.2–2.4)	2.2 (2.2–2.4)	2.3 (2.2–2.4)	0.568
Sodium (mmol/L)	141 (139–142)	140 (139–141)	141 (139–142)	0.294
Total cholesterol (mmol/L)	4.4 (3.8–5.3)	4.5 (4.1–5.3)	4.4 (3.8–5.3)	0.504
AST/ALT	1.2 (1–1.5)	1.1 (1–1.4)	1.2 (1–1.5)	0.416
BUN (mmol/L)	5.5 (4.5–7.3)	5.3 (4.6–7.5)	5.5 (4.5–7.3)	0.826
Creatinine (µmol/L)	78.9 (66–97.1)	87.8 (76.9–118.1)	78 (65.9–96.5)	0.123
Uric acid (μmol/L)	339.1 (286.9–424.6)	302.6 (248.8–385.8)	344.6 (290.9–424.7)	0.109
SUA/Cr ratio	4.2 (3.5–5.1)	3.3 (2.8–4.9)	4.2 (3.6–5.1)	0.025*
SUA/Cr ratio≤3.3, n (%)	36 (18.5)	11 (57.9)	25 (14.2)	<0.001*
D-dimer (mg/L)	0.4 (0.2–0.8)	0.6 (0.3–1.5)	0.4 (0.2–0.8)	0.101
Blood glucose (mmol/L)	5.6 (5–6.7)	5.4 (5.1–7.3)	5.7 (4.9–6.7)	0.937
Surgical types, n (%)
Transurethral cystolithotripsy with holmium laser	41 (21.0)	3 (15.8)	38 (21.6)	0.203
Ureteroscopic holmium laser lithotripsy	113 (57.9)	9 (47.4)	104 (59.1)
Percutaneous nephrolithotomy	41 (21.0)	7 (36.8)	34 (19.3)
Surgical positions, n (%)
Lithotomy	146 (74.9)	13 (68.4)	133 (75.6)	0.310
Supine	9 (4.6)	0 (0)	9 (5.1)
Prone	40 (20.5)	6 (31.6)	34 (19.3)
Anesthesia method, n (%)
General anesthesia	154 (79)	14 (73.7)	140 (79.5)	0.551
Spinal anesthesia	41 (21)	5 (26.3)	36 (20.5)
Anesthetics usage, n (%)
Midazolam	145 (74.4)	14 (73.7)	131 (74.4)	0.925
Dexmedetomidine	160 (82.1)	12 (63.2)	148 (84.1)	0.024*
Propofol	156 (80)	15 (78.9)	141 (80.1)	0.904
Sufentanil	154 (79)	15 (78.9)	139 (79)	0.998
Butorphanol	21 (10.8)	2 (10.5)	19 (10.8)	0.971
Dezocine	155 (79.5)	14 (73.7)	141 (80.1)	0.510
Duration of surgery (min)	100 (60–136)	90 (55–135)	101 (65–139)	0.297
Hypotension, n (%)	7 (3.6)	1 (5.3)	6 (3.4)	0.680
Vasoactive drugs usage, n (%)	18 (9.2)	1 (5.3)	17 (9.7)	0.529
Minimum body temperature (°C)	36.4 (36.3–36.5)	36.4 (36.3–36.5)	36.4 (36.3–36.5)	0.439
Intraoperative lactic acid level (mmol/L)	1.3 (1–1.6)	1.6 (1.2–1.9)	1.3 (1–1.6)	0.018*
Estimated blood loss volume (mL)	5 (2–20)	10 (2–30)	5 (2–20)	0.518
Total times of postoperative analgesics	1 (0–1)	1 (0–1)	1 (0–1)	0.594

Notes: *Indicates p-value <0.05 between delirium and non-delirium groups.

Abbreviations: ASA, American Society of Anaesthesiologists; ACEI, Angiotensin-Converting Enzyme Inhibitors; AST/ALT, Aspartate Transaminase/Alanine; BUN, Blood Urea Nitrogen; CHD, Coronary Heart Disease; COPD, Chronic Obstructive Pulmonary Disease; SUA/Cr ratio, Serum Uric Acid to Creatinine ratio.

Table 2 Analyses of Risk Factors for Postoperative Delirium

Variables	Univariate					Multivariate
	B	Wald	OR	95% CI	p-value	B	Wald	OR	95% CI	p-value
Age	0.078	4.130	1.081	1.003–1.166	0.042*	–	–	–	–	–
ASA status≥3	1.224	5.949	3.400	1.272–9.088	0.015*	1.399	6.378	4.050	1.368–11.991	0.012*
β-blockers	1.207	3.645	3.344	0.968–11.544	0.056	–	–	–	–	–
SUA/Cr ratio≤3.3	2.117	17.069	8.305	3.042–22.671	<0.001*	2.172	15.927	8.772	3.019–25.483	<0.001*
Intraoperative lactic acid level (mmol/L)	0.812	3.842	2.253	1.000–5.074	0.050	–	–	–	–	–
Dexmedetomidine	−1.126	4.719	0.324	0.117–0.896	0.030*	−1.122	3.758	0.326	0.105–1.012	0.053

Notes: *Indicates p-value <0.05. The Hosmer and Lemeshow goodness-of-fit test: χ² value=1.164, P=0.884.

Abbreviations: ASA, American Society of Anaesthesiologists; CI, Confidence Interval; OR, Odds Ratio; SUA/Cr ratio, Serum Uric Acid to Creatinine ratio.

Figure 3 The predictive value of the risk stratification score.

Notes: (A) The predictive risk of delirium according to the risk score (score 0–3). The POD incidence was 2% in score 0, 10.5% in score 1, 22.7% in score 2, and 42.9% in score 3 (P<0.001). (B) The predictive accuracy of risk stratification score by the ROC curve indicated that the AUC was 0.802 (P<0.001, 95% CI=0.698–0.907).

Abbreviations: AUC, Area Under Curve; POD, Postoperative Delirium; ROC, Receiver Operator Characteristic.

Table 3 Comparison of Clinical Outcomes in Both Groups

Outcomes	Delirium (n=19)	Non-Delirium (n=176)	p-value
Length of hospital stay (days)	15 (12–20)	12 (9–15)	0.006*
Septic shock	1 (5.3)	1 (0.6)	0.054
Fever	1 (5.3)	5 (2.8)	0.561
Pneumonia	0 (0)	1 (0.6)	0.742
ICU admission	1 (5.3)	6 (3.4)	0.680

Notes: *Indicates p-value<0.05 between delirium and non-delirium groups.

Abbreviation: ICU, Intensive Care Unit.