Table 3.
Association between minus 1 g/dL haemoglobin concentration and cognitive outcome.
| Cognitive outcome | Models Aa |
Models Bb,c |
||||||
|---|---|---|---|---|---|---|---|---|
| ß (95% CI) | p | Risk Ratio (95% CI) | p | ß (95% CI) | p | Risk Ratio (95% CI) | p | |
| Global cognitive functioningd | −0.07 (−0.15; 0.01) | 0.08 | 1.15 (1.02; 1.30) | 0.02 | −0.08 (−0.16; 0.01) | 0.08 | 1.16 (1.00; 1.35) | 0.05 |
| Memory | −0.09 (−0.24; 0.07) | 0.27 | 1.07 (0.80; 1.41) | 0.68 | −0.11 (−0.27; 0.06) | 0.21 | 1.09 (0.82; 1.45) | 0.56 |
| Language | 0.01 (−0.07; 0.09) | 0.78 | 0.62 (0.38; 1.02) | 0.06 | 0.01 (−0.07; 0.09) | 0.81 | n/ae | n/a |
| Attention-psychomotor speed | −0.19 (−0.33; −0.05) | 0.007f | 1.27 (1.09; 1.47) | 0.002f | −0.17 (−0.32; −0.02) | 0.02 | 1.32 (1.06–1.65) | 0.01 |
| Executive functioning | −0.02 (−0.12; 0.08) | 0.74 | 1.04 (0.39; 2.77) | 0.92 | −0.04 (−0.15; 0.07) | 0.51 | 1.05 (0.32–3.44) | 0.94 |
Data showing the association between haemoglobin concentration and cognitive outcome presented as ß (95% CI) per minus 1 g/dL haemoglobin for continuous outcomes (domain z-scores) and Risk Ratio's (95% CI) per minus 1 g/dL haemoglobin for dichotomous outcomes (impaired cognition).
Models A include haemoglobin concentration in g/dl, age, sex, education and a history of ischaemic stroke as dependant variables and cognitive outcome (domain z-scores or impaired cognition) as independent variable. Additionally, we applied a Bonferroni adjustment to correct for testing multiple cognitive domains.
Models B: same as model A but adding total CBF as dependant variable.
To assess the interaction between haemoglobin concentration and total CBF, the interaction term (haemoglobin*CBF) was additionally added to models B. We found no interaction between haemoglobin and total CBF in relation to cognitive outcome (p-values for interaction terms all >0.05).
Global cognitive functioning is the average z-score across the compound z-scores of memory, attention-psychomotor speed, language, and executive functioning. Overall, patients were classified as cognitively impaired when at least one domain was impaired.
Not applicable because of overfitting.
After correction for testing multiple cognitive domains these associations remained significant.