TITLE: 

Risk factors for Acute Kidney Injury in a South East Asian General Surgical Intensive Care Unit 

AIM:

Acute Kidney Injury (AKI) occurs in up to 47% of patients admitted to the General Surgical Intensive Care Unit (GSICU), and is associated with poor patient outcomes (1, 2). Studies have identified age and diabetes (2) as predictors of AKI. 

With an aging population and increasing incidence of diabetes in Singapore (3,4), this study aims to determine the risk factors for AKI in such a population. 

METHODOLOGY:

Following institutional review board approval, we retrospectively obtained data from 831 patients admitted to the GSICU of a tertiary hospital from 2015-2016. Patient demographics, clinical factors, and perioperative data were collected. Patients with pre-existing renal failure on dialysis were excluded.

 The primary outcome was AKI, as defined by Acute Kidney Injury Network criteria; secondary outcomes were in-hospital mortality and ICU length of stay. 

Univariate analysis was done using Pearson chi-square test for categorical variables, and independent sample t-test for quantitative variables. Variables with p<0.10 were included in multivariate stepwise logistic regression analysis.

RESULTS:

Incidence of AKI was 17.8%. Patients who developed AKI were more likely to be older, diabetic, have pre-existing renal dysfunction, cardiac pathology and perioperative hemodynamic instability. Within the ICU, they were noted to have lower haematocrit (HCT) and higher APACHE II scores. 

Multivariate analysis revealed diabetes (p=0.003, odds ratio (OR) 1.891, 95% confidence interval (CI) 1.250 – 2.859), lower haematocrit (p<0.001, OR 0.934, 95% CI 0.904 - 0.965), mean arterial pressure < 70mmHg (p=0.045, OR 4.443, 95% CI 1.037 – 19.032), and congestive heart failure (p=0.042, OR 2.671, 95% CI 1.036 – 6.881) to be independent risk factors.

Patients with AKI had a significantly higher mortality rate of 29.1% compared to 17.0% (p=0.001). Average ICU length of stay was 4.28 compared to 3.48 days (not significantly different).


CONCLUSION:

Acute Kidney Injury is a common complication in our ICU associated with increased mortality rates. Targeting modifiable risk factors such as anemia and hemodynamic instability may reduce incidence of Acute Kidney Injury.

REFERENCES:

1) Harris, D. G., et al. J Crit Care (2015)
2) Kheterpal, S., et al. Anesthesiology (2009)
3) Wong, L. Y., et al. J Diabetes (2017) 
4) Kaare, C., et al. Lancet (2009)