a randomized trial shows.
“Since 2005, active fever prevention in comatose patients has been advocated by the guidelines for 72 hours after an out-of-hospital cardiac arrest,” Christian Hassager, MD, of the University of Copenhagen, told this news organization. “Our study is the first randomized trial ever on this subject – and it challenges the guidelines.”
At 90 days, a primary endpoint – a composite of death from any cause or hospital discharge with a high Cerebral Performance Category score – occurred in 32.4% of those in the 36-hour group and 33.6% of those in the 72-hour group; mortality was 29.5% versus 30.3%, respectively.
The study was published online in The New England Journal of Medicine. The results were also presented at the Resuscitation Science Symposium during the American Heart Association scientific sessions.
No significant differences
Assessment of the two device-based fever-prevention strategies for the duration was a predefined, additional randomly assigned open-label intervention in the Blood Pressure and Oxygenation Targets in Post Resuscitation Care (BOX) trial, which involved comatose adult patients who had been resuscitated after out-of-hospital cardiac arrest at two Danish cardiac arrest centers.
The main BOX analysis compared different primary strategies in these patients in a two-by-two factorial design: higher versus lower blood pressure targets and higher versus lower oxygenation targets. They found no difference between the various strategies in terms of death and discharge from hospital in a poor neurologic state. Those results were presented at the European Society of Cardiology Congress on Aug. 27, and simultaneously published in separate articles in The New England Journal of Medicine.
For this current analysis, a total of 789 comatose patients (mean age, 62; 80% men) received device-based temperature control targeting 36° C for 24 hours followed by 37° C for either 12 or 48 hours (total intervention times, 36 and 72 hours, respectively) or until the patient regained consciousness.
Patients were kept sedated and were receiving mechanical ventilation during the temperature control at 36° C, the authors note. Target core body temperature was controlled using commercially available surface cooling at one of the sites in 286 patients (Criticool and Allon, Belmont Medical Technologies) and using intravenous cooling in 503 patients at the other site (Thermogard XP, and Cool Line Catheter, Zoll).
Body temperature was maintained at 37° C with the same type of device that had been used for 36° C during the initial 24 hours. If the patient awakened, cooling was terminated.
Physicians in both groups were permitted to use non–device-based fever treatment (that is, for a body temperature > 37.5° C) with drugs such as paracetamol, by uncovering the patient’s body, or both, at the discretion of the treating physician. Ice packs or pads were not used.
The primary outcome was a composite of death from any cause or hospital discharge with a Cerebral Performance Category of 3 or 4 (range, 1 to 5, with higher scores indicating more severe disability) within 90 days after randomization.
Secondary outcomes at 90 days included death from any cause and the Montreal Cognitive Assessment score (range, 0 to 30, with higher scores indicating better cognitive ability).
A primary endpoint event occurred in 32.3% of patients in the 36-hour group and in 33.6% of those in the 72-hour group (hazard ratio, 0.99). Mortality was 29.5% in the 36-hour group and 30.3% in the 72-hour group.
The median Montreal Cognitive Assessment scores were 26 and 27, respectively. No significant between-group differences in the incidence of adverse events were observed.
The authors concluded that “active device-based fever prevention for 36 or 72 hours after cardiac arrest did not result in significantly different percentages of patients dying or having severe disability or coma.”
Dr. Hassager added, “We will continue with a new trial where we will randomize to treatment as usual or immediate wakeup call and no temperature intervention at all.”