Correction for retest effects across repeated measures of cognitive functioning: a longitudinal cohort study of postoperative delirium

Table 4 Raw and corrected mean (standard deviation) GCP at each visit by group

	NSC			Delirium-Negative			Delirium-Positive
Visit	Raw GCP	Mean Difference-Corrected GCP	Predicted Difference-Corrected GCP	Raw GCP	Mean Difference-Corrected GCP	Predicted Difference-Corrected GCP	Raw GCP	Mean Difference-Corrected GCP	Predicted Difference-Corrected GCP
Month 0	58.14 (9.74)	N/A	N/A	58.51 (7.29)	58.51 (7.29)	58.51 (7.29)	54.73 (6.49)	54.73 (6.49)	54.73 (6.49)
Month 1	59.60 (9.30)	N/A	N/A	59.58 (7.82)	57.90 (7.75)	57.96 (8.3)	54.54 (7.07)	52.84 (6.97)	52.58 (7.43)
Month 2	60.20 (9.64)	N/A	N/A	61.01 (7.8)	58.86 (7.77)	58.88 (7.98)	56.82 (7.44)	54.72 (7.36)	54.61 (7.53)
Month 6	60.49 (9.68)	N/A	N/A	61.10 (7.51)	59.26 (7.42)	59.26 (7.59)	57.31 (7.29)	55.48 (7.18)	55.38 (7.32)
Month 12	N/A	N/A	N/A	61.44 (7.68)	59.56 (7.64)	59.56 (7.81)	57.10 (6.55)	55.26 (6.43)	55.17 (6.56)
Month 18	60.59 (9.71)	N/A	N/A	61.46 (7.85)	59.64 (7.77)	59.64 (7.93)	56.77 (7.7)	54.92 (7.64)	54.82 (7.79)

This table contrasts the mean absolute scores of the raw and retest-corrected General Cognitive Performance (GCP) across the three clinical groups of interest: non-surgical comparison group (NSC; n = 118), surgical patients who did not develop delirium (Delirium-negative; n = 426), and surgical patients who developed post-operative delirium (Delirium-positive, n = 134). Approaches 1 and 4 both utilized raw GCP data; however, Approach 1 only compared the delirium-positive and delirium-negative groups while Approach 4 first compared both surgical groups to the NSC group and subsequently performed post hoc tests to compare the delirium-positive and delirium-negative groups. Approach 2 utilized mean difference-corrected GCP and Approach 3 utilized predicted difference-corrected GCP

ISSN: 1471-2288