Determinants of cognitive outcome in survivors of out-of-hospital cardiac arrest.

Aim: To describe cognitive functioning with neuropsychological tests and examine predictors of cognitive outcome in adult survivors of out-of-hospital cardiac arrest (OHCA) of cardiac cause.

Method: The study was prospective and took place at the University hospital of North-Norway. Only patients eligible of neuropsychological assessment three months after OHCA were asked to participate. Cognitive test performance was compared to large samples of age-corrected normative data. General linear models were used to determine predictors of a cognitive composite score and performance on separate cognitive tests. The predictors assessed were coma duration, hypothermia treatment and time to restoration of spontaneous circulation. We aimed to control for demographic variables, medical comorbidity and affective symptoms.

Results: 45 survivors (4 women) completed the assessment. Neuropsychological tests of fine motor functioning, memory, attention and executive functions were significantly below normative means. Depending on the test, impairment ranged from 9 to 31%. For twenty-five survivors (56%), all cognitive tests were within the normal range. Shorter coma duration and induced hypothermia treatment were associated with favourable cognitive outcomes and explained 45% of the variability in the cognitive composite score. Coma duration was predictive across all cognitive tests, hypothermia treatment of specific tests of memory, attention and executive functioning.

Conclusions: Cognitive outcome was normal in more than half of the survivors. Shorter coma duration and induced hypothermia were associated with favourable cognitive outcomes in the participating survivors three months after OHCA. Institutional protocol number: 2009/1395.