BACKGROUND: Targeted temperature management (TTM) with therapeutic hypothermia is an integral component of postarrest care for survivors. However, recent randomized controlled trials (RCTs) have failed to demonstrate the benefit of TTM on clinical outcomes. We sought to determine if the pooled data from available RCTs support the use of prehospital and/or inhospital TTM after cardiac arrest. METHODS: A comprehensive search of SCOPUS, Elsevier's abstract and citation database of peer-reviewed literature, from 1966 to November 2016 was performed using predefined criteria. Therapeutic hypothermia was defined as any strategy that aimed to cool post-cardiac arrest survivors to a temperature ≤34°C. Normothermia was temperature of ≥36°C. We compared mortality and neurologic outcomes in patients by categorizing the studies into 2 groups: (1) hypothermia versus normothermia and (2) prehospital hypothermia versus in-hospital hypothermia using standard meta-analytic methods. A random effects modeling was utilized to estimate comparative risk ratios (RR) and 95% confidence intervals (CIs). RESULTS: The hypothermia and normothermia strategies were compared in 5 RCTs with 1389 patients, whereas prehospital hypothermia and in-hospital hypothermia were compared in 6 RCTs with 3393 patients. We observed no difference in mortality (RR, 0.88; 95% CI, 0.73- 1.05) or neurologic outcomes (RR, 1.26; 95% CI, 0.92-1.72) between the hypothermia and normothermia strategies. Similarly, no difference was observed in mortality (RR, 1.00; 95% CI, 0.97-1.03) or neurologic outcome (RR, 0.96; 95% CI, 0.85-1.08) between the prehospital hypothermia versus in-hospital hypothermia strategies. CONCLUSIONS: Our results suggest that TTM with therapeutic hypothermia may not improve mortality or neurologic outcomes in postarrest survivors. Using therapeutic hypothermia as a standard of care strategy of postarrest care in survivors may need to be reevaluated.
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Funding: This study was supported in part by the Walter B. Frommeyer Investigative Fellowship awarded to P.A. N.S.B. was supported by National Institutes of Health grant 5T32HL094301-07. N.P. was supported by National Institutes of Health grant 1T32HL129948-01A1. The authors declare no conflicts of interest. Reprints will not be available from the authors. Address correspondence to Navkaranbir S. Bajaj, MD, MPH, Division of Cardiovascular Medicine, Department of Radiology, Brigham and Women’s Hospital, 75 Francis St, Boston, MA 02115. Address e-mail to bajaj.navkaran@ gmail.com; Pankaj Arora, MD, FAHA, Division of Cardiovascular Disease, University of Alabama at Birmingham, 1670 University Blvd, Volker Hall B140, Birmingham, AL 35294. Address e-mail to email@example.com.
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