Fig. 2

Correlations between direct plasma Aβ measurements on Elecsys and measurements after immunoprecipitation (IP). The measured concentrations of A Aβ40, B Aβ42, and C the Aβ42/40 ratio in diluted IP-eluates (Elecsys IP-eluate, Y) are plotted against the corresponding measurements in plasma (Elecsys plasma, X). Points are colored by diagnostic group (red = Aβ+, blue = Aβ−). The diagonal dashed lines correspond to the identity lines. Spearman correlation coefficients and p-values are indicated. Aβ, amyloid-β; Aβ+, Aβ-positive: CSF Aβ42/40 ≤ 0.050; Aβ−, Aβ-negative: CSF Aβ42/40 > 0.050