Serum Anion Gap Predicts All-Cause Mortality in Critically Ill Patients with Acute Kidney Injury: Analysis of the MIMIC-III Database

Table 2

Relationship between anion gap and all-cause mortality in different models.

Variable	Crude model		Model I		Model II
	HR (95% CIs)	value	HR (95% CIs)	value	HR (95%CIs)	value
30-day all-cause mortality
Anion gap (mmol/L)	1.11 (1.10, 1.12)	<0.0001	1.11 (1.10, 1.12)	<0.0001	1.07 (1.06, 1.09)	<0.0001
Anion gap (tertile) (mmol/L)
<12	1.0 (ref)		1.0 (ref)		1.0 (ref)
≥12, <14	1.13 (1.00, 1.27)	0.0568	1.08 (0.96, 1.22)	0.2017	1.08 (0.91, 1.26)	0.3774
≥14	1.89 (1.71, 2.09)	<0.0001	1.81 (1.63, 2.00)	<0.0001	1.54 (1.33, 1.75)	<0.0001
for trend	<0.0001		<0.0001		<0.0001
90-day all-cause mortality
Anion gap (mmol/L)	1.10 (1.09, 1.11)	<0.0001	1.10 (1.09, 1.11)	<0.0001	1.08 (1.06, 1.10)	<0.0001
Anion gap (tertile) (mmol/L)
<12	1.0 (ref)		1.0 (ref)		1.0 (ref)
≥12, <14	1.13 (1.02, 1.25)	0.0216	1.08 (0.98, 1.20)	0.1340	1.09 (0.95, 1.25)	0.1452
≥14	1.78 (1.64, 1.94)	<0.0001	1.70 (1.56, 1.85)	<0.0001	1.55 (1.38, 1.73)	<0.0001
for trend	<0.0001		<0.0001		<0.0001
365-day all-cause mortality
Anion gap (mmol/L)	1.08 (1.08, 1.09)	<0.0001	1.09 (1.08, 1.09)	<0.0001	1.08 (1.06, 1.09)	0.0002
Anion gap (tertile) (mmol/L)
<12	1.0 (ref)		1.0 (ref)		1.0 (ref)
≥12, <14	1.14 (1.05, 1.25)	0.0019	1.10 (1.01, 1.19)	0.0344	1.14 (1.03, 1.24)	0.0122
≥14	1.64 (1.52, 1.76)	<0.0001	1.56 (1.45, 1.68)	<0.0001	1.46 (1.31, 1.60)	<0.0001
for trend	<0.0001		<0.0001		<0.0001

HR: hazard ratio; CI: confidence interval. Models were derived from Cox proportional hazards regression models. Crude model adjusted for: none. Model I adjusted for: age and gender. Model II adjusted for: age, gender, acute kidney injury stage, congestive heart failure, coronary artery disease, liver disease, stroke, respiratory failure, pneumonia, SIRS, potassium, albumin, platelet, BUN, PT, INR, APTT, WBC, creatinine, lactate, pH, bicarbonate, sodium, chloride, diabetes, bilirubin, renal replacement therapy, respiration rate, SPO2, heart rate, systolic blood pressure, diastolic blood pressure, temperature, Elixhauser comorbidity index, SOFA, and SAPSII.