Table 1

Sample characteristics, by availability of blood sample

Variables

Without blood sample

N = 408

With blood sample

N = 2520

P-value (T-test with F-value,

or chi-squared test)


Age in years (mean/sd) Missing values

75.4 (7.2) 0

75.0 (7.0) 7

F = 2.4, p = 0.27


Male sex (n/%)

159 (39.0%)

866 (34.4%)

X2 = 3.3, 1 df, p = 0.07


Ethnic identity

X2 = 1.9, 2 df, p = 0.39

'White'

77 (69.4%)

1674 (71.9%)

'Mixed'

17 (15.3%)

260 (11.2%)

'Black'

17 (15.3%)

395 (17.0%)

Missing values

97

191


Dementia (n/%)

47 (11.5%)

273 (10.8%)

X2 = 0.2, 1 df, p = 0.68


ICD depressive episode (n/%)

19 (4.7%)

125 (5.0%)

X2 = 0.1, 1 df, p = 0.79


Stroke (n/%)

35 (8.6%)

194 (7.7%)

X2 = 0.4, 1 df, p = 0.53

Missing values

2

7


Diabetes (n/%)

71 (17.5%)

471 (18.8%)

X2 = 0.4, 1 df, p = 0.53

Missing values

2

14


Hypertension (n/%)

295 (72.3%)

1841 (73.1%)

X2 = 0.1, 1 df, p = 0.75


Smoking (n/%)

176 (43.2%)

1141 (45.4%)

X2 = 0.7, 1 df, p = 0.41

Missing values

1

8


Family history of dementia (n/%)

75 (18.5%)

473 (18.8%)

X2 = 0.0, 1 df, p = 0.86

Missing values

2

8


Df = degrees of freedom

Teruel et al. BMC Medical Genetics 2011 12:43   doi:10.1186/1471-2350-12-43

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