Therapeutic hypothermia shows no benefit for in-hospital cardiac arrest

1. In this case-control matched study, patients who received therapeutic hypothermia had lower in-hospital survival rates and fewer favorable neurological outcomes.

2. The 1-year survival rate was similar between those receiving therapeutic hypothermia and those who did not.

Evidence Rating Level: 3 (Average)

Study Rundown: Randomized clinical trials have demonstrated that out-of-hospital cardiac arrest patients will benefit from therapeutic hypothermia. However, patients who suffer cardiac arrest in hospitals have a much quicker response time to resuscitation attempts, and few studies have investigated whether therapeutic hypothermia would benefit these patients. In this case-control study derived from the Get With the Guidelines (GWTG) Resuscitation Registry, patients who received therapeutic hypothermia had a slight but significantly decreased in-hospital survival rate. In addition, favorable neurological outcomes at discharge were also less frequent for those who received therapeutic hypothermia. Finally, using Medicare to assess longer-term survival, it was observed that the 1-year survival rate was similar between both groups.

While this type of study (case-control) can introduce many sources of bias, the overall study design and execution was strong, including a rigorous protocol to assign and match propensity scores for both groups in order to control for a number of confounding variables. Further, this study was well-powered. Though it’s unlikely that therapeutic hypothermia for in-hospital cardiac arrest patients is extremely harmful, it is likely that this practice is unable to reduce morbidity or mortality in this setting.

Click to read the study in JAMA

Relevant Reading: Hypothermia for intracranial hemorrhage after traumatic brain injury

In-Depth [case-control study]: As documented by the GWTG Resuscitation Registry, there were 117 005 patients with in-hospital cardiac arrest with return of spontaneous circulation across 674 participating hospitals, between 2002 and 2014. Of these, 1524 patients who were treated with hypothermia were matched to 3714 patients who were not treated with hypothermia according to a propensity score analysis. A multivariable logistic regression model was used to assess a patient’s likelihood of being treated with therapeutic hypothermia based on a number of factors including, age, sex, race, time and day of the week, initial cardiac arrest rhythm, location of arrest, comorbid conditions, medical conditions within 24 hours of arrest, duration of CPR and interventions in place at the time of the arrest. Overall, patients who received therapeutic hypothermia were less likely to survive to hospital discharge by 3.6% (CI₉₅ 6.2% to 0.9%). In addition, these patients were less likely to have a favorable neurological outcome by 4.4% (CI₉₅ 6.8 to 2.0%). Finally, by matching patients to their Medicare information, 706 patients treated with hypothermia were compared to 2035 controls for 1-year survival, which was similar between groups.

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