King's College London

Aim: The determinants of cognitive impairment and delirium during acute illness are poorly understood despite being common among older people. Anaemia is common in older people, and there is on-going debate regarding the association between anaemia, cognitive impairment and delirium, primarily in non-surgical patients. Methods: Using data from the Older Persons Surgical Outcomes Collaboration (OPSOC)2013 and 2014 audit cycles, we examined the association between anaemia and cognitive outcomes in patients, ≥65 years, admitted to five UK acute surgical units. On admission, the Confusion Assessment Method (CAM) was performed to detect delirium. Cognition was assessed using the Montreal Cognitive Assessment (MoCA) and two levels of impairment were defined as MoCA<26 and <20. Logistic regression models were constructed to examine these associations in all, and individuals ≥75 years only. Results: A total of 653 patients, median age of 76.5 (Interquartile range 73.0-80.0) years, 53% women, were included. Statistically significant associations were found between anaemia and age; polypharmacy; hyperglycaemia; and hypoalbuminaemia. There was no association between anaemia and cognitive impairment or delirium. The adjusted odds ratio (aOR) of cognitive impairment were aOR 0.95(95% CI 0.56-1.61) and 1.00(0.61-1.64) for MoCA <26 and <20, respectively. The aOR of delirium was 1.00(0.48-2.10) in patients with anaemia compared to those without. Similar results were observed for ≥75 age group. Conclusion: There was no association between anaemia and cognitive outcomes among older people in this acute surgical setting. Considering the retrospective nature of the study and possible lack of power, findings should be taken with caution.