Based on existing evidence and expert consensus, a multidisciplinary writing group organized by the American Heart Association (AHA) Emergency Cardiovascular Care Science Subcommittee released recommendations to improve the quality of adult and pediatric neurologic prognostication studies for survivors of cardiac arrest. This report was published in Circulation.
The writing group, which was composed of experts from adult and pediatric neurology, cardiology, emergency medicine, intensive care medicine, and nursing, examined relevant studies and existing practices of neurologic prognostication and withdrawal of life-sustaining treatment (WLST). WLST, often based on poor neurologic prognosis, is a major cause of death for patients resuscitated after cardiac arrest.
Recommendations for Design of Neurologic Prognostication Studies
Most neurologic prognostication studies reported in the cardiac arrest literature used indirect measures of brain injury severity following cardiac arrest. The AHA recommends neurologic prognostication be approached as index tests based on neurologic functions directly related to functional outcomes as well as quality of life.
The literature further reveals that the relationships between predictive variables and outcomes are not linear and may not be restricted to a single approach for optimizing the prediction of outcome; rather, combined findings of multiple predictive modalities should contribute to neurologic prognostication and the likelihood of survival.
Recommendations for Measures of Neurologic Outcomes
Current measures of neurologic function after cardiac arrest include the modified Rankin Scale and the Cerebral Performance Categories. In children, these measures include the Pediatric Cerebral Performance Categories, the King’s Outcome Scale for Childhood Injury, and the Pediatric Stroke Outcome Measure.
The writing group recommends the modified Rankin Scale version for adults as it can better discriminate between mild and moderate post-anoxic brain impairments as well as identify dependency issues related to severe cognitive impairment rather than just locomotor problems. The Pediatric Stroke Outcome Measure is widely used in pediatric studies, but King’s Outcome Scale for Childhood Injury is more sensitive to outcomes in children less than 2 years old and may be used as a complementary measure to Pediatric Stroke Outcome Measure.
Recommendations for Cessation of Dichotomization of Neurologic Outcomes
Dichotomizing neurologic outcomes as “good” or “poor” (based on the thresholds of common outcome measures) results in a loss of granularity and prevents measuring the evolution of individual outcomes over time. This also prevents pooling in meta-analyses due to the heterogeneity of outcome thresholds.
Recommendations for Reporting Cause of Death
Death is used as a neurologic outcome in common outcome measures, but these do not specify the actual cause of death. The AHA recommends the clarification of death in relation to neurologic prognostication by providing the mode of death (brain death or somatic/cardiac death), the extent of medical support with or without DNAR directives, and defining WLST as due to perceived neurologic futility, medicinal futility, or both.
Recommendations for Measures of Quality of Life
Although certain outcome measures are generally reliable to assess health-related quality of life after cardiac arrest, further studies are needed to understand the correlation between quality of life and neurologic function following cardiac arrest. Therefore, quality-of-life measures, including patient-reported and physician-reported outcomes, are recommended in prognostic studies for both adult and pediatric populations.
Recommendations for Timing of Outcome Assessment
In prognostication studies, the appropriate timing to assess the impact of the index test on neurologic outcomes should ensure that neurologic deficit has stabilized and that no associated comorbidities have occurred. Although 30 days after cardiac arrest is the minimum timing for measuring neurologic outcomes, recommended follow-up times longer than 30 days are desirable.
The AHA cautions against collecting neurologic outcomes at hospital discharge because some social functions and complex activities are difficult to assess within the hospital setting. Quality-of-life assessments are recommended at a minimum 3 months after cardiac rest, and again at 6 months and 1 year. Longer follow-up times are often necessary for assessing the youngest patients, especially as their brains continue to develop.
Recommendations for Sources of Bias
Two major sources of bias identified were self-fulfilling prophecy and sedation or medications. To avoid the former, the treating team should ideally be blinded to results; however, this is not generally feasible, and comatose resuscitated patients should be maintained with full medical support. Establishing a strict protocol for WLST is also recommended, including a description of cause of death in all patients. Sedatives and neuromuscular blocking drugs may interfere with neurologic prognostication; to avoid bias, the use of short-acting drugs is recommended.
Recommendations for Standards for Reporting
To achieve substantial quality of evidence, the AHA recommends avoiding indirectness (for example, providing a description of the cause of death), inconsistency (by adopting standardized definitions and terminology), imprecision, and incomplete reporting. Furthermore, adhering to highly suggested reporting standards like Standards for Reporting Diagnostic accuracy studies or Transparent Reporting of a Multivariable Prediction Model for Individual Prognosis or Diagnosis is recommended.
This article originally appeared on Neurology Advisor