The frequency, cost, and clinical outcomes of hypernatremia in patients hospitalized to a comprehensive cancer center

Purpose: To study the frequency of hypernatremia in hospitalized cancer patients and its impact on clinical outcomes and healthcare cost. Methods: Cross-sectional analysis of data obtained from patients admitted to the University of Texas M. D. Anderson Cancer Center over a 3-month period in 2006. The clinical outcomes and hospital costs were compared among hypernatremics, eunatremics, and hyponatremics (serum sodium values include >147, 135-147, and <135 mEq/L, respectively). Results: Of 3,446 patients with at least one serum sodium value, 51.4 % were eunatremic, 46.0 % hyponatremic, and 2.6 % hypernatremic with most of the hypernatremia (90 %) acquired during hospital stay. The multivariate hazard ratio (HR) for mortality in hypernatremic was 5-fold higher than eunatremic (HR for 90 days - 5.09 (95 % CI, 3.32-7.81); p < 0·01) and over 2-fold higher than hyponatremic (HR for 90 days - 2.79 (95 % CI, 1.91-4.11), p < 0.01). The length of hospital stay in hypernatremic was 2-fold higher than in hyponatremic and 4-fold higher than in eunatremic (e.g., 27 ± 22 days in hypernatremic vs. 6 ± 5 days in eunatremic; mean ± SD, p < 0.01). The hospital bill was higher for hypernatremic compared with the rest of the groups (46 % over eunatremic and 37 % over hyponatremic, p < 0.01 for both). Conclusions: Although hypernatremia was far less frequent than hyponatremia in the hospitalized cancer patients, most hypernatremia were acquired in the hospital and had substantially higher mortality, hospital stay, and hospital bills than eunatremic or even hyponatremic patients. Studies are warranted to determine whether avoidance of hypernatremia or its prompt and sustained correction improves clinical outcomes.