Hyponatremia’s Separate Effects on ICU Admissions and Length of Stay May Present Opportunity to Reduce Length of Stay Among Heart Failure Patients in Maryland

In Hyponatremia

By: James Pitt  May. 14, 2018

Hyponatremia is a common electrolyte disorder, defined as blood sodium levels under 135 mEq/L. Dexur has previously examined hyponatremia’s effect on ICU stays among patients with heart failure with major comorbidities (DRG 291) in Maryland.

A 2008 study found higher ICU admissions and length of stay in patients with hyponatremia. Dexur analysts examined whether this relationship holds for the subpopulation of patients with hyponatremia and heart failure with major complications (DRG-291). At hospitals in Maryland with over 5,000 CMS inpatient discharges per year, DRG 291 patients with hyponatremia had longer average lengths of stay than other DRG 291 patients. The effect ranged from an extra 9.38 days at University of Maryland Medical Center (Baltimore, MD) to an extra 0.7 days at Saint Agnes Hospital (Baltimore, MD).

Surprisingly, ICU stays did not drive this relationship. Hyponatremia increased the average length of stay and odds of ICU stay. But there was no relationship between those metrics.

This is surprising because the length of stay is used as a proxy variable for illness severity, and ICU patients, of course, tend to be more severely ill. However, this analysis omits a key variable: treatment. Intensive care patients are treated with more resources than general-population patients. This could lead to lower LOS increases in ICU patients with these comorbidities than in general-population patients with these comorbidities.

This finding implies that at some Maryland hospitals, patients with hyponatremia have long lengths of stay in the general population without being admitted to intensive care. These hospitals may have an opportunity to reduce the length of stay among DRG 291 patients with hyponatremia, possibly by admitting more of them to intensive care.


  1. Average length of stay at DRG 291 overall, with and without hyponatremia, and difference with vs without hyponatremia, with state and national comparisons for Sinai Hospital of Baltimore, MedStar Franklin Square Hospital Center, University of Maryland Baltimore Washington Medical Center, Peninsula Regional Medical Center, Suburban Hospital, Adventist Healthcare Shady Grove Medical Center, University Of Maryland Medical Center, Holy Cross Hospital, Saint Agnes Hospital, The Johns Hopkins Hospital, Greater Baltimore Medical Center, Carroll Hospital, and Anne Arundel Medical Center.


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James Pitt

James Pitt is a science writer with experience in medical devices and textbook publishing. His hobbies include reading, flintknapping, and squinting at RStudio. He received a bachelor's in Human Evolutionary Biology from Harvard.