Preoperative hypoalbuminemia was associated with acute kidney injury in high-risk patients following non-cardiac surgery: a retrospective cohort study

Table 4 Postoperative outcomes

	Total (n = 729)	All patients (n = 729)		P value	AKI patients (n = 188)		P value
	Total (n = 729)	Without postoperative AKI (n = 541)	With postoperative AKI (n = 188)	P value	Preoperative albumin ≥37.5 g/L (n = 90)	Preoperative albumin < 37.5 g/L (n = 98)	P value
On MV in ICU	390 (53.6%)	268 (49.6%)	122 (64.9%)	< 0.001	51 (56.7%)	71 (72.4%)	0.024
Duration of MV (h) ^a	26.9 (19.8, 34.0)	14.7 (11.1, 18.3)	53.4 (33.0, 73.8)	< 0.001	55.4 (21.5, 89.4)	51.9 (26.5, 77.4)	0.835
Length of ICU stay (d) ^b	2.5 (2.3, 2.8)	2.0 (1.8, 2.3)	4.0 (3.1, 4.9)	< 0.001	3.4 (2.1, 4.8)	4.5 (3.3, 5.7)	0.027
Number of postoperative complications except AKI ^c	0 (0, 1)	0 (0, 0)	0 (0, 2)	< 0.001	0 (0, 1)	1 (0, 3)	< 0.001
Postoperative hospital stay (d) ^d	13.7 (12.6, 14.8)	12.3 (11.3, 13.3)	17.8 (14.8, 20.9)	< 0.001	16.9 (11.8, 22.0)	18.7 (15.2, 22.2)	0.158
In-hospital mortality	14 (1.9%)	1 (0.2%)	13 (6.9%)	< 0.001	2 (2.2%)	11 (11.2%)	0.020
Total cost (10,000 dollars)	1.2 (0.7, 1.7)	1.1 (0.6, 1.6)	1.3 (0.9, 2.0)	< 0.001	1.2 (0.6, 1.8)	1.5 (1.0, 2.2)	0.011

Data are presented as number of patients (percentage), or median (interquartile range), unless otherwise indicated
ICU intensive care unit, MV mechanical ventilation
^a Results of patients requiring postoperative mechanical ventilation. Data were analyzed by Kaplan-Meier analysis and compared by log-rank test; results are presented as average (95% confidence interval);
^b Result of patients admitted to ICU. Data were analyzed by Kaplan-Meier analysis and compared by log-rank test; results are presented as average (95% confidence interval)
^c Including pulmonary infection, pleural effusion, atelectasis, respiratory failure, acute myocardial infarction, congestive heart failure, new-onset arrhythmia, hemodynamic insufficiency, stroke, venous thromboembolism, ileus, intra-abdominal abscess, wound infection, urinary tract infection, sepsis, surgical bleeding, digestive tract bleeding, acute liver injury, disseminated intravascular coagulation, anastomotic leakage, and wound dehiscence [see Additional file 2: Table S2]
^d Data were analyzed by Kaplan-Meier analysis and compared by log-rank test; results are presented as average (95% confidence interval)

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