Body Mass Index Is Associated with the Severity and All-Cause Mortality of Acute Kidney Injury in Critically Ill Patients: An Analysis of a Large Critical Care Database

Table 3

HRs (95 CIs) for mortality across groups of BMI.

Variable	Crude model		Model I		Model II
	HR (95 CIs)	value	HR (95 CIs)	value	HR (95 CIs)	value
30-day all-cause mortality
BMI (kg/m^2)	0.98 (0.98, 0.99)	<0.0001	0.99 (0.98, 0.99)	0.0002	0.99 (0.98, 1.00)	0.0092
BMI (category) (kg/m^2)
<18.5	1.16 (0.95, 1.42)	0.1438	1.14 (0.93, 1.39)	0.2147	0.96 (0.75, 1.22)	0.7228
≥18.5, <25	1.0(ref)		1.0(ref)		1.0(ref)
≥25, <30	0.77 (0.69, 0.85)	<0.0001	0.80 (0.72, 0.89)	<0.0001	0.87 (0.77, 0.99)	0.0287
≥30	0.74 (0.67, 0.82)	<0.0001	0.80 (0.72, 0.88)	<0.0001	0.87 (0.77, 0.98)	0.0250
90-day all-cause mortality
BMI (kg/m^2)	0.98 (0.97, 0.98)	<0.0001	0.98 (0.98, 0.99)	<0.0001	0.98 (0.98, 0.99)	<0.0001
BMI (category) (kg/m^2)
<18.5	1.31 (1.11, 1.54)	0.0012	1.29 (1.10, 1.52)	0.0021	1.05 (0.86, 1.28)	0.6311
≥18.5, <25	1.0(ref)		1.0(ref)		1.0(ref)
≥25, <30	0.76 (0.70, 0.83)	<0.0001	0.79 (0.72, 0.86)	<0.0001	0.84 (0.76, 0.93)	0.0012
≥30	0.72 (0.66, 0.78)	<0.0001	0.77 (0.71, 0.84)	<0.0001	0.79 (0.71, 0.88)	<0.0001
365-day all-cause mortality
BMI (kg/m^2)	0.97 (0.97, 0.98)	<0.0001	0.98 (0.97, 0.98)	<0.0001	0.98 (0.97, 0.98)	<0.0001
BMI (category) (kg/m^2)
<18.5	1.40 (1.23, 1.60)	<0.0001	1.38 (1.21, 1.58)	<0.0001	1.16 (0.98, 1.36)	0.0878
≥18.5, <25	1.0(ref)		1.0(ref)		1.0 (ref)
≥25, <30	0.73 (0.68, 0.79)	<0.0001	0.76 (0.71, 0.82)	<0.0001	0.80 (0.74, 0.88)	<0.0001
≥30	0.68 (0.63, 0.73)	<0.0001	0.73 (0.68, 0.79)	<0.0001	0.73 (0.66, 0.80)	<0.0001

HR: hazard ratio; CI: confidence interval. Models were derived from the Cox proportional hazards regression models. The crude model was adjusted for none. The Adjust I model was adjusted for age, gender, and ethnicity. The Adjust II model was adjusted for age, gender, ethnicity, congestive heart failure, cardiac arrhythmias, valvular disease, hypertension, uncomplicated diabetes, complicated diabetes, renal failure, liver disease, metastatic cancer, coagulopathy, alcohol abuse, anion gap, bicarbonate, glucose, creatinine, chloride, lactate, potassium, activated partial thromboplastin time, international normalized ratio, blood urea nitrogen, white blood cell, heart rate, systolic blood pressure, diastolic blood pressure, respiratory rate, temperature, SPO₂, ICU length of stay, AKI stage, SAPSII, and SOFA.