Pre-existing chronic kidney disease and acute kidney injury among critically ill patients.

BACKGROUND

The impact of pre-existing chronic kidney disease (CKD) and acute kidney injury (AKI) on health outcomes in critically ill patients is unclear. Yet, CKD complicated by AKI in critically ill patients is common.

OBJECTIVES

To compare risk of death within one-month of admission in critically ill patients with and without pre-existing CKD who developed AKI.

METHODS

A multicenter retrospective comparative study using medical records review was conducted. Study participants consisted of 826 adult patients who received mechanical ventilation for at least 6 h in the critical care units from January 2012 to December 2017. Assessment of kidney function was established by serum creatinine. Severity and staging of AKI were defined using RIFLE criteria: Risk, Injury, Failure, Loss and End stage of renal disease. Chronic kidney disease was defined as eGFR > 60 ml/mg/1.73 m on admission.

RESULTS

Pre-existing CKD was present in 55% of patients and 7% had AKI within 7 days of admission. The overall mortality rate among these patients was 87.3%. The mortality rate was highest in patients with CKD (70.1%) followed by that of patients without pre-existing CKD but with AKI (20.7%) and that of patients with pre-existing CKD (7.1%) and AKI. Risks associated with mortality were APACHE II score (1.03; 95% CI 1.02-1.05;(P<0.001) and AKI (1.68; 95% CI 1.12-2.5;P<0.01) in patients with pre-existing CKD. Only APACHI-II (1.03; 95% CI 1.0-1.1; p < 0.001) was predictive of death in patients without pre-existing CKD.

CONCLUSION

Pre-existing comorbid CKD increases risks of death among critically ill patients compared to patients without CKD and regardless of whether they develop AKI or not. Early identification of CKD and recognition of the risk for mortality among these patients may result in earlier intervention that could reduce mortality.