Addition of serum sodium into the MELD score predicts waiting list mortality better than MELD alone

In this study, we investigated the prognostic value of serum sodium and hyponatremia (less than or equal to130 mEq/L) in 262 cirrhotic patients consecutively listed, 19 of which died (7%), 175 survived (67%), and 68 under-went liver transplantation (26%) during 3 months of follow-up. Hyponatremia was present in 63% of patients who died, compared to 13% of those who survived (P < .001), whereas the proportion with elevated creatinine (greater than or equal to1.4 mg/dL) was low and similar in both groups (10.5 vs. 3%). Prevalence of hyponatremia was higher than that of elevated serum creatinine across all model for end-stage liver disease (MELD) categories. Using logistic regression, hyponatremia and serum sodium were significant predictors of mortality with concordance statistics (c-statistics) .753 for hyponatremia, .784 for sodium, .894 for MELD, .905 for MELD plus hyponatremia (P = .006 vs. MELD alone), and .908 for MELD plus serum sodium (P = .026 vs. MELD alone). Risk of death across all MELD scores was higher for patients with hyponatremia than without hyponatremia. Cox regression considering data within 6 months of follow-up yielded qualitatively similar results, with hyponatremia being a significant predictor of greater mortality risk with an odds ratio of 2.65 (P = .015). Each increase of 1 mEq/L of serum sodium level was associated with a decreased odds ratio of .95 (P = .048). Our results indicate that hyponatremia appears to be an earlier and more sensitive marker than serum creatinine to detect renal impairment and / or circulatory dysfunction in patients with advanced cirrhosis. In conclusion, addition of serum sodium to MELD identified a subgroup of patients with poor outcome in a more efficient way than MELD alone and significantly increased the efficacy of the score to predict waitlist mortality.