A Human Volunteer Study to Identify Variability in Performance in the Cognitive Domain of the Postoperative Quality of Recovery Scale

Background: The Postoperative Quality of Recovery Scale found lower than anticipated recovery in the cognitive domain. The definition of cognitive recovery did not allow for performance variability, and may have been too sensitive. This study aimed to examine variability in cognitive performance in volunteers. Methods: One hundred forty-three volunteers completed the cognitive domain questions at baseline, after 15 min and 40 min, and on days 1 and 3. Delivery via face-to-face interview was conducted for the first three measurements, and then randomized for day 1 and 3 measurements (face-to-face only, telephone only, telephone then face-to-face, face-to-face then telephone). Results: All volunteers answered orientation correctly. Mean change scores for other tests were positive, indicating a modest learning effect. There were no significant differences between methods of delivery (all P > 0.05). Due to variability in volunteers' performances, the authors propose a new scoring system to introduce a tolerance factor in scoring cognitive recovery. The proposed revised change from baseline scores are: orientation 0 or higher, digits forward -2 or higher, digits back -1 or higher, word recall -3 or higher, and word generation -3 or higher. This resulted in approximately 95% volunteers classed as recovered for each test item, and recovery for the domains ranged from 82.6 to 89.1%. The initial feasibility study was reanalyzed and cognitive recovery increased at all assessment times. At 3 days, cognitive recovery was found to increase from 33.5 to 86.4%. Conclusion: The authors recommend adoption of the new method for scoring cognitive recovery in the Postoperative Quality of Recovery Scale. Telephone or face-to-face delivery was equivalent and either method can be reliably applied.