Subjective impairment after cardiac surgeries: the relevance of postoperative cognitive decline in daily living.

OBJECTIVES: Postoperative cognitive decline (POCD) is a frequent complication after cardiac surgeries. It remains unclear how relevant this decline in psychometric results is for daily life. The aim of the study was to assess cognitive failures, as seen by patients and close relatives, on a quantitative level.
METHODS: In addition to an extensive neuropsychological test battery, we interviewed 82 patients with a modified version of the self-assessment cognitive failure questionnaire (s-CFQ) and 62 close relatives (mostly spouses) with the CFQ-for-others version (f-CFQ) before and 3 months after aortic valve replacement. The questionnaires evaluate the frequency of failures in daily living related to memory, attention, action and perception.
RESULTS: POCD occurred in all tests that had been applied to assess declarative memory functions; the mean performance dropped from baseline in these tests (P-values ranging from 0.033 and <0.001). The s-CFQ did not differ between baseline and postoperative assessment [baseline: mean 37.60, standard deviation (SD) 14.38; post: mean 36.22, SD 12.29] (t(0.05, 76) = 1.17; P = 0.246). However, the assessment by others was worse in the f-CFQ after surgery (baseline: mean 8.02, SD 4.51; post: mean 9.58, SD 6.11) (t(0.05, 61) = 2.61; P = 0.012). All changes were observed in questions related to memory and attention failures only. Higher (worse) rates in f-CFQ change scores correlated with neuropsychological change scores, namely in pictorial memory (mistakes) (r = 0.35; P = 0.003) and word fluency (correct answers) (r = -0.29; P = 0.014). Additionally, those patients with worse f-CFQ change scores (>1 SD) from baseline had clearly worse outcomes in word fluency (t(0.05, 60) = 2.53; P = 0.007) and non-verbal learning (t(0.05, 60) = 2.66; P = 0.005). The effects remained significant when controlled for depression/anxiety scores.
CONCLUSIONS: The result demonstrates that cognitive side-effects could have a perceivable impact on daily living functions. However, slight deficits are more realized by others than by the patients themselves. Correlations between ratings by others and psychometric cognitive measures indicate that assessment by others is more reliable than self-assessment.