Hyponatremia Predicts Mortality in Guillain-Barré Syndrome

Nancy A. Melville

October 01, 2015

CHICAGO — Patients with Guillain-Barré syndrome (GBS) show increases in the incidence of hyponatremia, and this condition was a significant independent predictor of inpatient mortality, a new study shows.

"Hyponatremia in GBS is concerning because it leads to higher hospital complications, prolonged hospital stay, increased hospital costs, adverse discharge disposition (patients not discharged to home), and in-hospital mortality," first author Kavelin Rumalla, from the University of Missouri-Kansas City School of Medicine, told Medscape Medical News.

Their research was presented here at the American Neurological Association (ANA) 2015 Annual Meeting.

Hyponatremia is the most common electrolyte abnormality detected in hospitalized patients, the authors write, and often arises as a complication of acute illness. Despite the observed increase of hyponatremia in GBS in recent years, research on its incidence and role in inpatient mortality with GBS is lacking.

In their report, Rumalla and colleagues evaluated the incidence, risk factors, and short-term outcomes of hyponatremia in a cohort of 54,778 patients with GBS in the Nationwide Inpatient Sample from 2002 to 2012.

They found the overall incidence of hyponatremia among patients with GBS increased significantly over the decade, from 5.3% in 2002 to 11.8% in 2011; he standardized mortality rate among hospitalized GBS patients with hyponatremia was 20.5%, compared with 11.6% among hospitalized GBS patients without hyponatremia (P < .0001).

In a multivariable analysis, patients who developed hyponatremia were also more likely to die during hospitalization than those without the condition (odds ratio, 1.26, 95% confidence interval, 1.06 - 1.49; P = .008). 

"We were surprised to find that hyponatremia was an independent predictor of mortality and other poor outcomes in GBS patients," Rumalla said.

The strongest risk factors for the development of hyponatremia in GBS included age older than 40 years, Medicaid insurance, and treatment with intravenous immunoglobulin (IVIG) (all P < .0001). 

"Our results suggest that hyponatremia in GBS patients may be also related to both nonmodifiable factors, such as patient's age and pre-existing comorbidity, as well as potentially modifiable factors, such as IVIG as the choice of treatment," Rumalla said.

With hyponatremia in GBS linked to extensive potential adverse issues, the findings suggest the need for increased awareness and prevention, he added.

"These results suggest that hyponatremia in GBS is a critical complication and future research is indicated to understand if monitoring and treating hyponatremia in GBS patients will lead to better patient outcomes."

According to Minhtri K. Nguyen, MD, director of consultative nephrology at the Ronald Reagan UCLA Medical Center in Los Angeles, California, the findings are consistent with the known effect of hyponatremia in increasing the risk for death in hospitalized patients in general.

"Therefore, it is not surprising that hyponatremia was an independent predictor of inpatient mortality in GBS patients," he told Medscape Medical News. "[But] it is important to note that this study did not demonstrate that hyponatremia was causally associated with mortality in GBS patients."

Even with treatment, Dr Nguyen noted that the effects on mortality are uncertain.

"It is unknown whether treatment of hyponatremia will reduce the mortality in this patient population," Dr Nguyen said.

"As a correlate, hyponatremia is associated with increased mortality in patients with congestive heart failure (CHF); however, treatment of hyponatremia has not been shown to reduce mortality in patients with CHF."

Dr Nguyen agreed that there is a need for awareness of the potential development of hyponatremia in GBS.

"Physicians should be aware that treatment of GBS with intravenous immune globulin (IVIG) can result in the development of both pseudohyponatremia and true hyponatremia."

"Hyponatremia due to the syndrome of inappropriate antidiuretic hormone secretion (SIADH) has also been associated with GBS," he said.

Kavelin Rumalla and Dr Nguyen have disclosed no relevant financial relationships.

American Neurological Association (ANA) 2015 Annual Meeting. Abstract S613. Presented September 27, 2015.


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