Calculated Serum Osmolality, Acute Kidney Injury, and Relationship to Mortality after Percutaneous Coronary Intervention

BACKGROUND: Data on the associations between serum osmolality (sOsmo) and acute kidney injury (AKI) as well as short- and long-term mortality in patients with coronary artery disease (CAD) undergoing percutaneous coronary intervention (PCI) are limited. OBJECTIVES: To investigate the association between sOsmo and development of AKI and clinical outcomes in patients undergoing PCI. METHODS: We investigated 1,927 consecutive patients undergoing PCI from the registry of a single center. Patients were divided into quartiles according to sOsmo at admission (Q1-Q4). sOsmo was calculated using the following equation: (1.86 × serum sodium [mmol/L]) + (glucose [mg/dL] / 18) + (blood urea nitrogen [mg/dL] / 2.8) + 9. The primary endpoint was AKI, per Kidney Disease: Improving Global Outcomes (KDIGO) definition. The secondary endpoints were 30-day and 1-year all-cause mortality. RESULTS: Patients with the highest sOsmo (Q4) were older and more likely female, with significantly more cardiovascular risk factors and comorbidities compared to those with lower sOsmo (Q1-Q3). Incidence of AKI was highest in Q4 and lowest in Q2. In the multivariate logistic regression model, high sOsmo independently predicted the development of AKI (OR 2.00, 95% CI 1.26-3.19, p = 0.003). Patients with Q4 had a higher risk of 1-year mortality compared to patients with Q2 (HR 2.11, 95% CI 1.10-4.15; p = 0.031), but not after adding AKI to the multivariate model (HR 1.71, 95% CI 0.87-3.39; p = 0.12). CONCLUSION: sOsmo is a valid and easily obtainable predictor of AKI after PCI. High sOsmo is associated with increased risk of AKI and 1-year mortality in patients undergoing PCI. Further research is warranted to clarify whether the use of an sOsmo-directed hydration protocol might reduce the incidence of AKI in patients undergoing PCI.