Probing the association between AKI and cardiovascular outcomes

Patients hospitalized with AKI have higher subsequent risks of heart failure, atherosclerotic cardiovascular events, and mortality than their counterparts without AKI, but these higher risks may be due to differences in pre-hospitalization patient characteristics, including the baseline level of kidney function, the rate of prior kidney function decline, and the proteinuria level, rather than AKI itself. Among 2,177 adult participants in the Chronic Renal Insufficiency Cohort (CRIC) study who were hospitalized in 2013-2019, we compared subsequent risks of heart failure, atherosclerotic cardiovascular events, and mortality between those with serum creatinine-based AKI (495 patients) and those without AKI (1,682 patients). We report both crude associations and associations sequentially adjusted for pre-hospitalization characteristics including estimated glomerular filtration rate (eGFR), eGFR slope, and urine protein/creatinine ratio (UPCR). Compared to patients hospitalized without AKI, those with hospitalized AKI had worse kidney function pre-hospitalization (eGFR 42 vs 49 ml/min/1.73m2), faster chronic loss of kidney function pre-hospitalization (eGFR slope -0.84 vs -0.51 ml/min/1.73m2/yr), and more proteinuria pre-hospitalization (UPCR 0.28 vs 0.16 g/g); they also had higher pre-hospitalization systolic blood pressure (130 vs 127 mmHg) (p<0.01 for all comparisons). Adjustment for pre-hospitalization patient characteristics attenuated associations between AKI and all three outcomes, but AKI remained an independent risk factor. Attenuation of risk was similar after adjustment for absolute eGFR, eGFR slope, or proteinuria, individually or in combination. Pre-hospitalization variables including eGFR, eGFR slope, and proteinuria confound associations between AKI and adverse cardiovascular outcomes, but these associations remain significant after adjusting for pre-hospitalization variables.

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