Effects of certain pre-analytical factors on the performance of plasma phospho-tau217

Table 6 Plasma p-tau217 concentrations across different pre-analytical handling conditions

CSF Aβ42/Aβ40	Total (n = 100)	Aβ⁺ (n = 50)	Aβ⁻ (n = 50)	P-value Aβ⁻ vs Aβ⁺
Plasma p-tau217, pg/ml
Cond 1: thaw at RT, NC	0.31 (0.42–0.20)	0.40 (0.51–0.31)	0.22 (0.31–0.17)	< 0.001
Cond 2: thaw at RT, C	0.23 (0.32–0.14)	0.31 (0.43–0.25)	0.15 (0.21–0.13)	< 0.001
Cond 3: thaw on ice, NC	0.26 (0.35–0.19)	0.34 (0.47–0.27)	0.20 (0.23–0.16)	< 0.001
Cond 4: thaw on ice, C	0.23 (0.33–0.16)	0.32 (0.44–0.26)	0.16 (0.21–0.14)	< 0.001
Plasma p-tau217, pg/ml
Cond 1: thaw at RT, NC, fxt-1	0.30 (0.42–0.22)	0.37 (0.48–0.30)	0.22 (0.28–0.16)	< 0.001
Cond 2: thaw at RT, C, fxt-1	0.19 (0.28–0.15)	0.27 (0.34–0.21)	0.16 (0.18–0.12)	< 0.001
Cond 3: thaw at RT, NC, fxt-2	0.31 (0.39–0.22)	0.36 (0.47–0.31)	0.23 (0.30–0.17)	< 0.001
Cond 4: thaw at RT, C, fxt-2	0.19 (0.29–0.15)	0.27 (0.35–0.20)	0.16 (0.19–0.13)	< 0.001
Cond 5: thaw at RT, NC, fxt-3	0.31 (0.42–0.23)	0.40 (0.47–0.32)	0.24 (0.30–0.19)	< 0.001
Cond 6: thaw at RT, C, fxt-3	0.21 (0.27–0.16)	0.27 (0.37–0.22)	0.17 (0.20–0.14)	< 0.001

Data are shown as median (Interquartile range). Group differences were analyzed using the Mann–Whitney test. Abbreviations: Aβ⁺Amyloid-β positive, Aβ⁻ Amyloid-β negative, C Centrifugation, Cond Condition, fxt Freeze–thaw cycle, NC Non-centrifugation, RT Room temperature

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