Supplementary Material for: The Prognostic Importance of Serum Sodium for Mortality among Critically Ill Patients Requiring Continuous Renal Replacement Therapy

<b><i>Background:</i></b> Serum sodium derangement is common in critically ill patients requiring continuous renal replacement therapy (CRRT). We aimed to assess the association between serum sodium before and during CRRT with mortality. <b><i>Methods:</i></b> This is a historical cohort study of 1,520 critically ill patients receiving CRRT from December 2006 through November 2015 in a tertiary hospital in the United States. Using logistic regression analysis, we used serum sodium before CRRT, mean serum sodium, and serum sodium changes during CRRT to predict 90-day mortality after CRRT initiation. <b><i>Results:</i></b> Compared with the normal serum sodium levels, the odds ratio (OR) of 90-day mortality in patients with serum sodium before CRRT of 143–147 and ≥148 mmol/L were 1.45 (95% CI 1.03–2.05) and 2.24 (95% CI 1.33–3.87), respectively. There was no significant increase in 90-day mortality in serum sodium of ≤137 mmol/L. During CRRT, the mean serum sodium levels of ≤137 (OR 1.41; 95% CI 1.01–1.98) and ≥143 mmol/L (OR 1.52; 95% CI 1.14–2.03) were associated with higher 90-day mortality. The greater serum sodium changes during CRRT were associated with higher 90-mortality (OR 1.35; 95% CI 1.21–1.51 per 5-mmol/L increase). <b><i>Conclusion:</i></b> Before CRRT initiation, hypernatremia and during CRRT, hypo- and hypernatremia were associated with increased mortality.