Development and validation of the Cerebral Performance Categories-Extended (CPC-E)

Optimizing resuscitation efforts after cardiac arrest (CA) requires valid and reliable measurements of functional outcomes. The Cerebral Performance Category (CPC), the historical "gold" standard outcome measure post-CA, lacks psychometric validation. The purpose of this study was to establish the psychometric properties of a revised CPC: the CPC-Extended (CPC-E).

The study had two phases: We established content validity of the CPC-E by identifying existing domains in the CPC, by adding new domains following a literature review, and iterative input from a panel of CA and rehabilitation experts. We tested the CPC-E's feasibility, intra-rater (IR) reliability and inter-rater reliability (IRR) using retrospective reviews of the electronic medical records (EMR) and "in-person" in-hospital administration.

The CPC-E has 10 domains. For both IR and IRR record reviews, 5/10 domains had frequent missing data and in three instances, intraclass correlation coefficients (ICC) could not be calculated. Of the scores that could be calculated, ICC ranged from poor to high (n=30; 0.46-1.0) and poor to high (n=50; -0.16 to 0.93) for IR and IRR, respectively. No data were missing for the "in-person" IRR for the 10 domains and ICC ranged from good to excellent (n=26; 0.79-1.00). In-hospital and post-discharge domains were completed in under 7 min.

The CPC-E is a valid and clinically feasible outcome measure for describing post-CA impairment and disability status. In-person hospital administration of the CPC-E yields more complete data and good to excellent inter-rater reliability compared to retrospective EMR review.