Acute kidney injury in Staphylococcus aureus bacteraemia: a recurrent events analysis

Abstract

Objectives: To estimate risk factors for acute kidney injury (AKI) and the effect of AKI on mortality in Staphylococcus aureus bacteraemia, while taking into account recurrent AKI episodes, competing risks, time-varying variables, and time-varying effects.

Methods: We performed an unplanned analysis using data from a multicentre cohort study of patients with Staphylococcus aureus bacteraemia (SAB). The primary outcome was cumulative incidence of AKI, according to Kidney Disease Improving Global Outcomes definitions.

Results: We included 453 patients in this study of whom 194 (43%) patients experienced one or more AKI episodes. Age (hazard ratio (HR) 1.013, 95% CI 1.001-1.024), Charlson comorbidity index (HR 1.07, 95% CI 1.01-1.14), prior chronic kidney disease (HR 1.76, 95% CI 1.28-2.42), septic shock (HR 3.28, 95% CI 2.31-4.66), persistent bacteraemia (HR 1.53, 95% CI 1.08-2.17), and vancomycin therapy (HR 1.80, 95% CI 1.05-3.09) were independently associated with AKI, but flucloxacillin, cefazolin, rifampicin, and aminoglycoside therapy were not. After adjustment for confounders and immortal time bias, AKI was associated with an increased risk of 90-day mortality (HR 4.26, 95% CI 2.91-6.23).

Discussion: The incidence of AKI in SAB is high and a substantial proportion of patients develop recurrent episodes of AKI after recovery. AKI is specifically linked to the use of vancomycin and not to anti-staphylococcal penicillins. The clinical outcome of patients with SAB complicated by AKI is worse than previously estimated.

Keywords: Acute kidney injury; Anti-staphylococcal penicillins; Clinical epidemiology; Cohort study; Staphylococcus aureus bacteraemia.