Table 3.

Multivariable models for 90-day mortality (dependent variable) in the 6 CKD/AKI groups (independent variable)

Variable	Model 1 aHR (95% CI)	P	Model 2 aHR (95% CI)	P
no-CKD
no-AKI	Reference		Reference
AKI 1	1.50 (1.13–1.99)	0.005	1.50 (1.13–1.98)	0.005
AKI ≥2	2.45 (1.92–3.12)	<0.001	2.44 (1.92–3.11)	<0.001
CKD
no-AKI	1.06 (0.81–1.40)	0.657	1.07 (0.82–1.41)	0.609
AKI 1	1.19 (0.89–1.60)	0.238	1.19 (0.89–1.60)	0.245
AKI ≥2	2.23 (1.71–2.91)	<0.001	2.22 (1.70–2.89)	<0.001
Age, per 1 yr	1.02 (1.01–1.03)	<0.001	1.02 (1.01–1.03)	<0.001
African American	0.88 (0.75–1.02)	0.098	0.89 (0.76–1.04)	0.127
Male gender	1.08 (0.93–1.26)	0.325	1.08 (0.93–1.26)	0.321
Diabetes	0.89 (0.74–1.08)	0.239	0.89 (0.74–1.08)	0.239
Systolic heart failure	0.68 (0.43–1.09)	0.111	—
Anemia	1.29 (1.01–1.66)	0.046	1.29 (1.00–1.65)	0.049
Nonrenal SOFA ≥4	1.38 (1.16–1.66)	<0.001	1.39 (1.16–1.66)	<0.001
Mechanical ventilation	2.22 (1.88–2.62)	<0.001	2.21 (1.87–2.60)	<0.001
RBC transfusion	1.32 (0.89–1.99)	0.171	—
Exposure to statins	0.68 (0.57–0.81)	<0.001	0.67 (0.56–0.80)	<0.001

APACHE II score was not included in the models due to collinearity with the SOFA score; aHR, adjusted hazard ratio; AKI, acute kidney injury; APACHE II, Acute Physiology and Chronic Health Evaluation II; CI, confidence interval; CKD, chronic kidney disease; RBC, red blood cell; SOFA, Sequential Organ Failure Assessment.

Data are aHRs and 95% CIs for 90-day mortality by Cox proportional hazard regression. Model 1 includes all tested variables, whereas model 2 includes variables of deemed particular clinical relevance (age, race, gender, diabetes), together with additional variables that were retained through backward selection (cut-off for retention: P < 0.10).