Hospitalized AKI

The primary outcome of interest was time to first hospitalized AKI, defined by a ≥50% increase from nadir to peak inpatient SCr measurement. This definition is adapted from the Kidney Disease Improving Global Outcomes (KDIGO) AKI guidelines,²⁶ and is more stringent to reduce false positives and improve specificity.²⁷ We used inpatient SCr measurements only to define hospitalized AKI to reduce the risk of misclassifying progression of CKD as AKI. We staged AKI according to KDIGO guidelines²⁶ and included: Stage 1; peak inpatient SCr 1.5–1.9 times nadir Scr; stage 2; peak inpatient SCr 2.0–2.9 times nadir Scr, and stage 3; peak inpatient SCr ≥3.0 times nadir Scr. AKI Hospitalizations were ascertained through participant self-report and hospital queries and confirmed via medical records review.^28,29 SCr values measured during these hospitalizations were systematically abstracted and organized to determine AKI status. Follow-up was through December 31, 2017.