Measuring outcome after cardiac arrest: construct validity of Cerebral Performance Category

Approximately half of the survivors of cardiac arrest have cognitive impairments due to hypoxic brain injury. To describe the outcome after a cardiac arrest, the Cerebral Performance Category (CPC) is frequently used. Although widely used, its validity is still debatable.

To investigate the construct validity of the Cerebral Performance Category in survivors of a cardiac arrest. Participants were 18 years and older that survived a cardiac arrest more than six months.

Cross-sectional design. A method to administer the CPC in a structured and reproducible manner was developed. This 'Structured CPC' was administered by a structured interview. Construct variables were Cognitive Failure Questionnaire (CFQ), Barthel Index (BI), Frenchay Activity Index (FAI), Community Integration Questionnaire (CIQ) and Quality of Life after Brain Injury (Qolibri). Associations were tested based on Spearman correlation coefficients.

A total of 62 participants responded. In 58 (94%) patients the CPC was determined, resulting in CPC 1 (48%), CPC 2 (23%) and CPC 3 (23%). The CPC-scoring correlated significantly with the CFQ (r=-0.40); BI (r=-0.57); FAI (r=-0.65), CIQ (r=-0.53) and Qolibri (r=-0.67).

In this study we developed the 'Structured CPC' to improve the transparency and reproducibility of the original CPC. A moderate correlation between the 'Structured CPC' and the constructs 'activities', 'participation' and 'quality of life' confirmed the validity of the 'Structured CPC'.

The 'Structured CPC' can be used as an instrument to measure the level of functioning after cardiac arrest.