The prognostic implications of preoperative hypernatremia are unknown. We sought to determine whether preoperative hypernatremia is a predictor of 30-day perioperative morbidity and mortality.

We conducted a cohort study using the American College of Surgeons-National Surgical Quality Improvement Program and identified 908,869 adult patients undergoing major surgery from approximately 300 hospitals from the years 2005 to 2010. We followed the patients for 30-day perioperative outcomes, which included death, major coronary events, wound infections, pneumonia, and venous thromboembolism. Multivariable logistic regression was used to estimate the odds of 30-day perioperative outcomes.

The 20,029 patients (2.2%) with preoperative hypernatremia (>144 mmol/L) were compared with the 888,840 patients with a normal baseline sodium (135-144 mmol/L). Hypernatremia was associated with a higher odds for 30-day mortality (5.2% vs 1.3%; adjusted odds ratio [aOR], 1.44; 95% confidence interval [CI], 1.33-1.56), and this finding was consistent in all subgroups. The odds increased according to the severity of hypernatremia (P < .001 for pairwise comparison for mild [145-148 mmol/L] vs severe [>148 mmol/L] categories). Furthermore, hypernatremia was associated with a greater odds for perioperative major coronary events (1.6% vs 0.7%; aOR, 1.16; 95% CI, 1.03-1.32), pneumonia (3.4% vs 1.5%; aOR, 1.23; 95% CI, 1.13-1.34), and venous thromboembolism (1.8% vs 0.9%; OR, 1.28; 95% CI, 1.14-1.42).

Preoperative hypernatremia is associated with increased perioperative 30-day morbidity and mortality.