January 2011

Hypothermia Therapy for Cardiac Arrest: Not Enough Proof 

I would like to express my concern about the front page headline and story in the November issue that trumpeted "Hypothermia Tx Underused After Cardiac Arrest." The lead sentence declares, "Therapeutic hypothermia is the only therapy proven to decrease mortality and improve neurologic outcomes in comatose patients after cardiac arrest..."

ACEP NEWS readers might wish to consider that this therapy has been "proven" to do no such thing.

It may seem incredible, but the sum total of even halfway decent evidence for any beneficial effect rests on a total of two studies, now both almost 9 years old. One of these studies had a grand total of 77 patients (that's not a misprint: 43 in one group, 34 in the other). It found no significant difference in mortality and a claimed a "good outcome" difference with a P value of .046, meaning that a single additional patient categorized as a poor outcome would have led to that end point being nonsignificant as well. The second study had more patients (275 in all: less than 150 in each group) but similarly tiny differences. The lower border of the 95% confidence interval for the claimed favorable outcome was 1.08, again only a patient or two from crossing the line of unity. The 14% difference in mortality is less impressive when it is noted that the normothermia patients were twice as likely to have diabetes and 50% more likely to have coronary heart disease. Even then, the upper limit of the confidence interval for this outcome was 0.95 !

Don't we ever learn? Even large, blinded studies often give results that are later disproved. Two small, old, nonblinded studies with razor-thin margins do not "prove" anything and should be considered inadequate both for policy pronouncements and for banner headlines.

Michael Heller, MD
New York

In Defense of Flu Shots 

I disagree with Dr. Brian Zachariah's statement that influenza vaccination of health care personnel lacks "proven beneficience" (Letters, November 2010, p. 2), as several studies have shown decrements in staff absenteeism and nosocomial transmission of influenza in highly vaccinated health care worker cohorts. Influenza vaccination should be mandatory as a condition of employment in the same fashion rubella immunity, tuberculosis testing, and hepatitis B immunity are. Just as patients are empowered to ask if their health care provider has washed his or her hands, they should be empowered to inquire regarding influenza vaccination status.

Amesh A. Adalja, MD

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