Cognition as independent predictor of functional outcome after cardiac arrest

Background
Cognitive function is often impaired for cardiac arrest (CA) survivors as an effect of hypoxic-ischemic brain injury. An important factor in CA recovery is global functional outcome, commonly assessed with the modified Rankin Scale (mRS). Little is known about the role of cognition as a potential predictor of outcome following CA.

Objective
To investigate cognitive function at hospital discharge as a predictor of global functional outcome at 1-month post-discharge. Our hypothesis was that cognitive function would be a significant independent predictor of functional outcome after adjusting for sociodemographic and medical factors.

Method
Adult CA survivors were recruited at Columbia University Medical Center, New York, in the ongoing Psychological Predictors of Recovery after Acute Cardiac Events (PACE) Study. Cognition was measured with the Telephone Interview for Cognitive Status Modified (TICS-M) at hospital discharge, and mRS was the functional outcome scale 1 month later. We analyzed our data with stepwise logistic regressions: 1) unadjusted; 2) adjusted for age, sex, educational attainment, race/ethnicity, time from CA to return of spontaneous circulation; 3) additionally adjusted for depressive symptoms (Patient Health Questionnaire-8) at
discharge.

Results
In our cohort of 112 participants (median age=56, 62% male) with completed TICS-M at discharge, 71% scored <36 indicating cognitive impairment, and 61% had mRS scores >3 equivalent to poor functional outcome at 1-month. Higher TICS-M scores at discharge independently predicted lower risk of poor 1-month mRS scores in all regression models, OR=0.84 (95% CI [0.74, 0.94]), p <.01 (model 3). Women had a greater risk of poor functional outcome. Hispanic participants had greater chances of good functional outcome.

Conclusion
Indicated cognitive impairment was a significant independent predictor of poor functional outcome after CA beyond the effects of demographics and CA downtime. This emphasizes the importance of targeting cognition in rehabilitation interventions, but also to identify other risk factors that could impede post-CA recovery.