Predictive Value of Anion Gap for Acute Kidney Injury Progression and Outcomes

BACKGROUND Anion gap (AG) is a cheap blood test, but the relationship between the AG at the onset of AKI and the progression and prognosis of AKI is unclear. This study explored the relationship between the AG at the onset of AKI and the progression and prognosis of AKI. MATERIAL AND METHODS We retrospectively analyzed data from a multicenter randomized study on an AKI early warning system. Univariate analysis, multivariate logistic regression, and curve fitting were used to assess the relationship between the AG at the onset of AKI and the AKI progression and prognosis of patients with AKI. RESULTS A total 5731 patients were included in our study. We found that AG at the onset of AKI was associated with 14-day AKI progression, 14-day dialysis, and 14-day mortality, and the adjusted ORs were 1.07 (1.04, 1.09), 1.09 (1.04, 1.15), and 1.10 (1.07, 1.14), respectively. Further curve fitting analysis found that there was a nonlinear correlation between the AG at the onset of AKI and 14-day AKI progression and 14-day mortality, and there was a linear correlation between the AG at the onset of AKI and 14-day dialysis. When the AG was >10 mmol/L, 14-day AKI progression and 14-day mortality were significantly increased. CONCLUSIONS An increase of AG at the onset of AKI was associated with an increased risk of 14-day AKI progression, 14-day dialysis, and 14-day mortality. Especially when the AG exceeded 10 mmol/L, the 14-day AKI progression and 14-day mortality were significantly increased, and the AG showed a linear correlation with 14-day dialysis.