Data Collection
AKI was identified by the presence of ICD-9 diagnosis codes of 584.5
(acute kidney failure with lesion of tubular necrosis), 584.6 (acute
kidney failure with lesion of renal cortical necrosis), 584.7 (acute
kidney failure with lesion of renal medullary necrosis), 584.8 (acute
kidney failure with other specified pathological lesion in kidney), or
584.9 (acute kidney failure, unspecified) in any of the listed
diagnoses. The identification of AKI using ICD-9 diagnosis code has a
specificity of 98% but a sensitivity of 17% and are likely to capture
a more severe spectrum of AKI, compared with KDIGO serum
creatinine-based
criteria.8,9
Clinical characteristics, treatments, and outcomes during
hospitalization were identified using ICD-9 codes (Table S1). Clinical
characteristics included age, sex, race, year of hospitalization,
alcohol consumption, certain comorbidities (obesity, anemia, diabetes
mellitus, hypertension, dyslipidemia, coronary artery disease,
congestive heart failure, atrial flutter/fibrillation, chronic kidney
disease, and cirrhosis), and acute conditions (sepsis, volume depletion,
seizure, gastrointestinal bleeding, ventricular arrhythmia/cardiac
arrest). Treatments included gastric lavage, non-invasive and invasive
mechanical ventilation, blood component transfusion, and renal
replacement therapy. Outcomes included end-organ failure (respiratory,
circulatory, liver, neurological or hematological failures), and
in-hospital mortality. Resource utilization included length of hospital
stay and hospitalization cost.