Quality-of-life and formal functional testing of survivors of out-of-hospital cardiac arrest correlates poorly with traditional neurologic outcome scales

Study hypothesis: The traditional (and unvalidated) five-point Cerebral Performance Category (CPC) score at hospital discharge does not correlate with the results yielded by a validated functional status instrument and subjective quality-of-life assessment. Methods: We compared CPC scores with the results of prospective standardized testing after discharge in survivors of out-of-hospital cardiac arrest. Consenting survivors were tested with the validated Functional Status Questionnaire (FSQ), a subjective quality-of-life assessment, and traditional CPC scoring. Results: Of the 3,130 arrests during the 52 months of the study, 93 patients survived. Thirty-five patients were tested (71% of those eligible at the time of follow-up). Of these patients, 34% said their quality of life was worse, 38% said it was the same, and 28% said it was better than before the cardiac arrest. Fifty-four percent of patients scored normally on all FSQ subscales, but the remainder had an average 2.1 areas (of 6) with significant impairment. CPC score correlated very poorly with quality-of-life rating and with all scores and subscores on the FSQ. A CPC of 1 on discharge (supposedly normal function) had a sensitivity of 78%, a specificity of 43%, a positive predictive value of 64%, and a negative predictive value of 60% for quality of life the same as or better than that before arrest. With regard to ability to predict the presence of any major areas of impairment on the FSQ, the respective figures were 32%, 43%, 43%, and 32%. Conclusion: The CPC score, relied on as a measure of functional outcome in cardiac arrest, correlates poorly with subsequent subjective quality of life and with validated objective functional testing instruments, and conclusions based on it are suspect. Future researchers should employ standardized testing instruments.