Association of baseline blood glucose levels with 30-day mortality in patients with acute kidney injury: a retrospective cohort study.

Abstract

The mortality rate is high in patients with acute kidney injury (AKI). Hyperglycemia and hypoglycemia alone can increase the morbidity and mortality of patients with AKI. Up to now, no relevant studies have analyzed the relationship between different blood glucose levels and mortality in AKI patients. Therefore, exploring the relationship between baseline blood glucose level and 30-day mortality in patients with AKI can provide early warning information for disease prognosis and provide reference basis for reasonable level of blood glucose control. This retrospective cohort study was obtained from the Medical Information Mart for Intensive Care III (MIMIC-III) database. Patients had experienced AKI within 48 hours of admission. AKI was diagnosed according to the Kidney Disease: Improving Global Outcomes (KDIGO) guidelines. Data on patients' baseline blood glucose level on admission was retrieved, and the outcome indicator was 30-day mortality. A multivariate Cox regression analysis and smoothed curve fitting were used to assess the relationship between the baseline blood glucose level and 30-day mortality. The covariates used for adjustment were those in the patient's baseline data. A total of 14,449 AKI patients were screened. The overall 30-day mortality rate was 17.6%. Patients with blood glucose levels of 6.36-7.35 mmol/L on admission had the lowest 30-day mortality risk. The multivariate Cox regression model and smoothed curve fitting revealed a U-shaped relationship between the baseline blood glucose level and 30-day mortality after adjusting all the covariables of the baseline data. The inflection point occurred at 5.52 mmol/L. The effect size was 0.773 [hazards ratio (HR) =0.773; 95% confidence interval (CI): 0.614-0.975, P=0.030] on the left side of the inflection point, and 1.077 (HR =1.077; 95% CI: 1.059-1.097, P<0.001) on the right side. The blood glucose of patients with AKI should be controlled at a reasonable level and should not be lower than 5.52 mmol/L, and the optimal control level needs further study. The limitation of this study is that there are some confounding factors in the retrospective study.