Unbiased estimates of cerebrospinal fluid β-amyloid 1–42 cutoffs in a large memory clinic population

Table 4 Cox proportional HRs (95% CIs) for clinical progression to Alzheimer’s disease-type dementia in nondemented subjects

CSF Aβ₄₂ cutoff	HR (95% CI)	Log-likelihood ratio	χ²
<550 pg/ml	5.14 (2.96–8.93)^a	−327.85	n.a.
<615 pg/ml	7.44 (3.74–14.79)^a	−324.66	6.38^b

Analyses were adjusted for age and sex. Data are from the subsample of nondemented sample with at least 6 months follow-up available seen between 2001 and 2007. The event rate was 33%, and about 13% of subjects were lost to follow up per year
Abbreviations: CSF Cerebrospinal fluid, Aβ ₄₂ β-Amyloid 1–42, n.a. Not applicable
^a p = 0.0001
^bDecrease in χ² p < 0.01