Fig. 2: Comparison among fluid biomarkers on predicting Aβ PET positivity in cognitively impaired patients of the BioFINDER-2 cohort.

a,b, Prediction of Aβ PET positivity in cognitively impaired participants (n = 304) from the BioFINDER-2 cohort, using a single-cutoff (a) and a two-cutoffs (b) approach, respectively. In the first approach, the threshold was calculated, maximizing sensitivity and fixing specificity at 90%. In the second approach, the lower threshold was obtained by maximizing specificity with sensitivity fixed at 95%, whereas the upper threshold was obtained by maximizing sensitivity while fixing specificity at 95%. Participants who fall between these two cutoffs were classified in the intermediate group. Dots and error bars represent the actual statistic and 95% CI (from bootstrapped n = 1,000 samples with replacement), respectively. c, Bootstrapped differences (n = 1,000 resamples with replacement stratifying by the output) between the statistics using plasma %p-tau217 (reference) and CSF biomarkers are shown in c for both single cutoff and two cutoffs. The horizontal dashed line is plotted at zero, representing the lack of difference between plasma and CSF biomarkers. We considered plasma and CSF biomarkers clinically equivalent if the 95% CI of the mean difference included zero and clinically superior if it did not include zero and favored plasma (>0). Differences in the number of participants in the intermediate group were scaled to a maximum of 1 to be comparable with the other differences. Dots and error bars represent the mean and 95% CI estimate from a bootstrapped sample. Vertical dashed lines represent the maximal statistical value possible (1). For the intermediate value plots, colored bars represent the actual percentage and the error bar the 95% CI. d, Histograms represent the distribution of the data colored by the imaging biomarker status. The vertical black line represents the threshold derived from the first approach (a), and red lines represent the lower and upper thresholds from the second approach (b). Aβ PET positivity was assessed as Centiloids ≥ 37. CSF, cerebrospinal fluid; CI, confidence interval; NPV, negative predictive value; PPV, positive predictive value.