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Wednesday, June 04, 2014
News from the AAN Annual Meeting: Should Hyperosmolar Therapy Be Used in Primary ICH Patients?
By Thomas R. Collins

PHILADELPHIA—A new study calls into question the use of hyperosmolar therapy for treating intracerebral hemorrhage (ICH). In a review of outcomes from a registry of patients with ICH, investigators said those treated with hyperosmolar therapy experienced significantly worse outcomes than those who did not receive the treatment.

The study — presented here at the AAN Annual Meeting in April — reviewed data from the Ethnic/Racial Variations of Intracerebral Hemorrhage (ERICH) trial, a multicenter study led by the University of Cincinnati. The trial focuses on finding risk factors for ICH among Caucasians, African-Americans, and Hispanics, and is thought to be the largest epidemiological, prospective, case-control ICH registry available.

Hyperosmolar therapy involves administering agents by bolus or infusion to reduce intracranial pressure (ICP), which can be life-threatening. In this study, the agents used were either mannitol or hypertonic saline or both; they act by increasing osmotic gradient across the blood-brain barrier, and thus reduce intracellular water content, especially in vasogenic edema conditions.

“However, very few studies have actually looked at the outcomes,” said Manan Shah, MD, chief resident in the department of neurology at the University of Texas Health Science Center at San Antonio, one of the centers involved in the ERICH study. “The objective of our study was to identify the effect of hyperosmolar therapy on three-month functional outcomes in the primary ICH population.”

He acknowledged that a major obstacle in evaluating the data was matching hyperosmolar patients with reasonable controls. [The trial, which was not randomized, used prospective, observational data.]

“One of the challenges in the study was to adjust multiple confounders of severity, which can affect the treatment decision,” Dr. Shah said.

To address this, researchers used a “propensity-scoring” model, a method to reduce bias by adjusting for all the background information regarding treatment selection. Patients treated with hyperosmolar therapy were matched with those who had not received this therapy but who were considered to share the same treatment probability, using several criteria, Dr. Shah said. Those criteria included age, the location of the hemorrhage, log ICH volume, craniotomy, the presence of intraventricular hemorrhage, and their grade on the Glasgow Coma Scale — factors that help determine the ICH score, which predicts 30-day mortality.

Of 790 ERICH subjects for whom sufficient data were available, 145 had been given hyperosmolar therapy as of the end of 2012. They were matched with controls, for whom there were no significant differences in all the variables considered in the propensity scoring model analysis.

Using the Modified Rankin Scale, they considered a three-month score of 3 (slight disability) or lower to be a “good” outcome, while anything over 3 was a “bad” outcome. [The scale measures the degree of disability or dependence in daily living activities from 0, for no disability, to 6 for death.]

Approximately 77 percent — 112 of the 145 patients who received hyperosmolar therapy — had a bad outcome, while 33 had a good outcome. Among those who did not receive hyperosmolar treatment, only 92 had a bad outcome, while 53 had a good outcome (p =.0055).

“In our study, the use of hyperosmolar therapy was associated with worse three-month outcomes even after matching for variables associated with worse outcomes,” Dr. Shah said. “This questions the efficacy and safety of hyperosmolar therapy in primary ICH.”

There are a few reasons why hyperosmolar therapy might yield worse outcomes, Dr. Shah said. “We believe that the problems with the use (of the therapy) in primary ICH are related to the difference in pathophysiology. There is a component of cytotoxic edema and a mass effect of the clot itself, which are refractory to hyperosmolar therapy.” He added that disruption of the blood-brain barrier might also play a role.

Dr. Shah said the study was limited in that the data are not truly randomized. Plus, the effects of mannitol compared with hypertonic saline couldn’t be assessed because many patients actually received both.

“The data [were] also limited regarding the strength of the agent, the duration of the therapy, and treatment setting,” he said.

More work is needed, he said, to further understand the role of this therapy for these patients — specifically, to define the patient populations that might benefit versus those who might not, the outcomes associated with the different hyperosmolar agents used, and the outcomes related to administration by bolus or infusion.

Read the full story with commentary from outside experts in the June 5 issue of Neurology Today. Our previous coverage of ICH is available here: http://bit.ly/ICH-NT.

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