Introduction: Acute kidney injury (AKI) increases morbidity and mortality in several acute illnesses. Here, we examine the incidence, risk factors, and in-hospital outcomes of AKI in patients hospitalized for aneurysmal subarachnoid hemorrhage (aSAH).
Methods: The Nationwide Inpatient Sample was queried from 2002 and 2011 for all emergency hospitalizations (age≥18) with a primary diagnosis of aSAH and a secondary diagnosis of AKI. Patients with chronic renal disease, renal transplant, or trauma were excluded from the analysis. The effect of various patient factors on AKI incidence and its impact on length of stay (LOS), in-hospital costs, and in-hospital mortality was examined in bivariate and multivariate analyses.
Results: Of 250,437 total hospitalizations for aSAH, the overall incidence of AKI was 4.0% (n=10,450) and increased from 2.1% in 2002 to 5.7% in 2011 (p<0.0001). The strongest multivariate predictors of AKI were 60-74 age group (OR: 1.43, 95% CI: 1.31-1.56), 75+ age group (OR: 1.81, 95% CI: 1.63-2.00), male gender (OR: 1.80, 95% CI: 1.69-1.87), Black race (OR: 1.45, 95% CI: 1.35-1.55), Medicaid insurance (OR: 1.29, 95% CI: 1.19-1.40), congestive heart failure (OR: 2.13, 95% CI: 1.98-2.28), liver disease (OR: 2.42, 95% CI: 2.13-2.75), fluid/electrolyte disorder (OR: 3.10, 95% CI: 2.95-3.27), and HIV (OR: 2.24, 95% CI: 1.66-3.01) (all p<0.0001). Aneurysmal coiling (OR: 0.81, 95% CI: 0.75-0.87) and clipping (OR: 0.75, 95% CI: 0.70-0.80) decreased the likelihood of suffering AKI (all p<0.0001). Cardiac arrest, septic shock, and acute lung injury were in-hospital complications that increased the odds of AKI (all p<0.0001). AKI occurrence in aSAH increased the mean LOS by 7.2 days and mean total costs by $28,813 (all p<0.0001). After adjusting for confounding factors, aSAH related AKI patients had increased likelihood of moderate to severe disability (OR: 2.03, 95% CI: 1.89-2.19, p<0.0001) and in-hospital death (OR: 2.14, 95% CI: 2.03-2.26, p<0.0001).
Conclusion: The incidence of AKI in hospitalized aSAH patients has increased over the past decade and is both detrimental to hospital costs and patient prognosis. We identified patient-centered risk factors for AKI, allowing for the close surveillance of patients at the highest risk for AKI.