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

Abstract

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.