ELISA measurement of specific non-antigen-bound antibodies to Aβ1-42 monomer and soluble oligomers in sera from Alzheimer's disease, mild cognitively impaired, and noncognitively impaired subjects

Table 3 Power analysis for anti-Aβ1-42 monomer antibody levels

Specified % Difference Between Means	NCI (μg/mL)	AD (μg/mL)	# Samples Required Per Group (80% power, p < 0.05)
20%	0.440	0.528	512
25%	0.440	0.550	328
30%	0.440	0.572	228
40%	0.440	0.616	129
50%	0.440	0.660	83

The mean concentrations for anti-Aβ monomer antibodies in NCI specimens were determined for pooled data from undissociated and dissociated serum samples. The mean anti-Aβ antibody level in AD subjects was specified to be increased by a given percentage (20-50%) from this NCI antibody concentration, and for each percentage the number of samples per group required to achieve 80% statistical power at a significance level of 0.05 was calculated. Approximately 328 samples per group would have been required to detect statistical significance for the observed differences of 25.7% in this study between NCI and AD means. (AD = Alzheimer's disease; NCI = aged noncognitively impaired)

ISSN: 1742-2094