Association between acute kidney injury and in-hospital mortality in patients undergoing percutaneous coronary interventions

Background: Acute kidney injury (AKI) post percutaneous coronary intervention (PCI) is associated with increased mortality but both death and AKI share common risk factors. Moreover, the effect of a high contrast dose, a known modifiable risk factor for AKI, on mortality is unknown. The aim of our study was to analyze the association between AKI and in-hospital mortality post PCI after adjustment for confounding by common risk factors.

Methods and results: This study was performed using a regional registry of all patients undergoing PCI in Michigan. Primary end points were AKI (serum creatinine increase >0.5 mg/dL) and all-cause in-hospital mortality. Propensity matching was performed, with each AKI patient matched to 4 controls. Attributable risk fraction and the exposed index number of AKI for mortality were calculated within the propensity-matched cohort. Between 2010 and 2013, 92 317 patients underwent PCI, of whom 2141 (2.3%) developed AKI. We matched 1371/2141 patients with AKI to 5484 controls. AKI was strongly associated with mortality (odds ratio=12.52, 95% confidence interval 9.29-16.86) in the propensity-matched cohort. The attributable risk fraction for mortality of AKI was 31.4% (95% confidence interval 26.8%-37.5%), and one death could be prevented for every 9 cases of AKI successfully avoided. The independent impact of a high contrast dose at time of PCI on in-hospital mortality risk was weak (adjusted odds ratio 1.19, 95% confidence interval 0.97-1.45).

Conclusions: Nearly one-third of the in-hospital mortality post PCI is attributable to AKI. Preventing 9 cases of AKI could potentially prevent one death. These study findings stress the need for developing effective AKI preventive strategies beyond minimization of contrast dose.