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Table 2 Characteristics of the study population and subgroups in total and stratified by amyloid-PET status

From: Comparison of ELISA- and SIMOA-based quantification of plasma Aβ ratios for early detection of cerebral amyloidosis

  Study population CN subgroup aMCI subgroup
Total Aβ− Aβ+ Total Aβ− Aβ+ Total Aβ− Aβ+
Number (%) 199 161 (81) 38 (19) 161 137 (85) 24 (15) 38 24 (63) 14 (37)
Mean age (SD), years 70 (6) 69 (6) 72 (5)b 69 (6) 69 (6) 71 (5) 71 (7) 69 (6) 74 (6)
Female, n (%) 89 (45) 72 (45) 17 (45) 73 (45) 61 (45) 12 (50) 16 (42) 11 (46) 5 (36)
Mean education (SD), years 14 (3) 14 (3) 14 (4) 14 (3) 14 (3) 14 (4) 14 (4) 14 (4) 14 (3)
APOE-ε4 carriers/homozygous, n (%) 92/7 (46) 70/5 (43) 22/2 (58) 82/6 (51) 65/5 (47) 17/1 (71)a 10/1 (26) 5/0 (21) 5/1 (36)
Median MMSE (IQR), /30 29 (2) 29 (2) 29 (2)a 29 (2) 29 (2) 29 (2) 29 (2) 29 (1) 27 (3)a
Median ELISA plasma Aβ1–42/Aβ1–40 (IQR) 0.17 (0.03) 0.18 (0.03) 0.15 (0.02)d 0.18 (0.03) 0.18 (0.03) 0.15 (0.02)d 0.17 (0.02) 0.18 (0.03) 0.16 (0.01)b
Median ELISA plasma Aβ1–42/t-tau (IQR) 1.23 (0.50) 1.32 (0.49) 1.00 (0.29)d 1.25 (0.49) 1.29 (0.49) 1.02 (0.34)c 1.21 (0.58) 1.41 (0.51) 0.89 (0.27)d
Median SIMOA plasma Aβ1–42/Aβ1–40 (IQR) 0.26 (0.06) 0.26 (0.06) 0.21 (0.05)d 0.26 (0.06) 0.26 (0.05) 0.21 (0.05)d 0.24 (0.07) 0.28 (0.06) 0.22 (0.03)c
Median SIMOA plasma Aβ1–42/t-tau (IQR) 0.93 (0.41) 0.99 (0.39) 0.73 (0.24)d 0.94 (0.37) 0.99 (0.38) 0.74 (0.27)c 0.92 (0.45) 1.14 (0.33) 0.70 (0.21)d
  1. aMCI amnestic mild cognitive impairment, β-amyloid, CDR Clinical Dementia Rating, CN cognitively normal, ELISA enzyme-linked immunosorbent assay, IQR interquartile range, MMSE Mini-Mental State Examination, SIMOA single molecule array, t-tau total tau. p values reflect comparisons between Aβ−ve and Aβ+ve groups: ap <  0.05; bp <  0.01; cp <  0.001; dp <  0.0001