Hypertonic saline appears to be an appealing addition to the current therapeutic armamentarium to treat cerebral edema. A retrospective study published by Yildizdas, et al.(1) concluded the effectiveness of hypertonic saline over mannitol in cerebral edema. However, two primary endpoints demonstrating efficacy of hypertonic saline over mannitol merit critical scrutiny.

First, outcome variable of "duration of comatose state" included all patients irrespective of their survival status. Failure to censor this time-to-event ‘duration of coma’ variable by mortality in this study is a major methodological flaw in evaluating treatment efficacy. Indeed, more aptly definable endpoint would be the "duration of resolution of abnormal mental status (or length of time to recovery from coma)".

Second, a P-value 0.003 in Table II while comparing the outcome of mortality (proportion) appears erroneous(1)? Using factual data about mortality and survival given by authors in their study, the calculated P value is 0.07. To substantiate this point further, we conducted a simple logistic regression with mortality as dependent binary variable and type of hyperosmolar therapy (categorical variable with 3 levels of treatment) as predictor using data provided by authors in the study. Only mixed treatment group was a significant prognostic predictor for survival of children with cerebral edema (OR: 4; 95% CI; 1.0 to 15.8; P= 0.049). Similarly, though odds of survival were three times higher with hypertonic saline treatment as compared to mannitol (Odds ratio 3.16), yet it failed to produce any significant 95% CI (0.91 to 10.9, P= 0.07).

To conclude, this study simply offers evidence that hypertonic saline is about as effective as mannitol (certainly not more) and is safe and effective alternative to mannitol.

Bhavneet Bharti,
Assistant Professor,
Advanced Pediatric Center,
PGIMER,,Chandigarh 160 012, India.
Email: [email protected]