AKI requiring new need for dialysis (AKI-D) after cardiac surgery is associated with significant mortality as high as 60% and greater utilization of healthcare resources. The incidence of AKI-D ranges from 1.7% - 3% which have been reported mainly in Caucasian populations. Non-white ethnicity is a risk factor for AKI-D. Given the multiethnic local population, we thus aim to identify if the incidence of AKI-D differs in the local population and the associated risk factors. 	 

With IRB approval, data from 2780 patients, who had undergone cardiac surgery with cardiopulmonary bypass between August 2008 and July 2012, were obtained prospectively. Patients who were on dialysis were excluded. The primary outcome was acute kidney injury with new need for dialysis. Binary logistic regression was used to determine significant predictors of new need for dialysis in patients who underwent cardiac surgery.

The incidence of new need for dialysis locally was 3.1%. Preoperative anaemia, acute haemodilution, blood transfusion, the Malay population (Malays versus Chinese and Indians), EUROSCORE LOG and eGFR factors independently increase the risk for dialysis postoperatively. Diabetes was found to not increase the risk for new need dialysis despite a greater percentage of diabetic patients requiring dialysis. (Table 1)
 
Patients with new need for dialysis had double the length of hospitalisation stay (P=0.001), 5.6 times the length of ICU stay (P<0.001) and increase in ICU mortality to 25% (P<0.001).

The incidence of AKI-D is much higher in the local multiethnic population compared to the Western population. Malays have a higher incidence compared to the other races, suggesting a genetic predisposition. The high prevalence of DM and pre-DM in this population is probably the reason why DM did not feature as an independent risk factor for AKI-D. Modifiable risk factors of preoperative anaemia, blood transfusion and acute haemodilution should be treated aggressively to reduce the incidence of AKI-D.

Important risk factors for acute kidney injury requiring dialysis after cardiac surgery in an Asian population