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Table 2 BBMs intra- & inter-variability in AD vs. non-AD

From: Short-term variability of Alzheimer’s disease plasma biomarkers in a mixed memory clinic cohort

Biomarker

Population

No. of Samples

Mean plasma concentration (pg/mL, 95% CI)

Intra-individual variability CV (%, 95% CI)

Inter-individual variability CV (%, 95% CI)

CVA (%)

Aβ40

Total

128

103.2 (98.7, 107.6)

5.2 (4.4; 6.0)

10.0 (8.4; 11.9)

Low QC

4.7

 

AD

71

96.9 (93.1, 100.6)

4.1 (3.3; 5.0)

7.1 (5.5; 8.7)c

High QC

7.5

 

non-AD

57

111.0 (102.3, 119.7)

6.2 (4.9; 7.5)

12.5 (9.3; 16.2)c

Mean

6.1

Aβ42

Total

128

5.4 (5.1, 5.7)

5.9 (5.0;6.7)

14.7 (12.2; 17.3)

Low QC

7.8

 

AD

71

5.0 (4.7, 5.2)

4.5 (3.6; 5.5)c

12.2 (9.2; 15.3)

High QC

4.3

 

non-AD

57

6.0 (5.3, 6.6)

7.2 (5.4;8.8)c

16.9 (12.2; 21.8)

Mean

6.05

Aβ42/Aβ40

Total

128

0.052 (0.050, 0.054)

3.3 (2.8;3.8)

10.1 (8.2; 12.0)

  

AD

71

0.051 (0.049, 0.054)

3.4 (2.7; 4.1)

11.2 (8.3; 14.1)

Mean

6.075d

non-AD

57

0.053 (0.050, 0.055)

3.2 (2.5; 3.9)

8.4 (5.9; 10.8)

  

Ptau181

Total

128

8.8 (8.0, 9.6)

7.0 (6.0; 8.1)

20.5 (16.8; 24.3)

Low QC

21

 

AD

71

8.6 (7.9, 9.3)

6.9 (5.6; 8.5)

15.1 (11.5; 18.8)c

High QC

5.8

 

non-AD

57

9.1 (7.5, 10.7)

7.2 (5.5; 8.8)

26.3 (18.4; 34.0)c

Mean

13.4

Ptau217

Total

128

0.7 (0.6, 0.7)

9.3 (7.9; 10.8)

27.3 (21.9; 32.4)

Low QC

15.6

 

AD

71

0.8 (0.7, 0.9)b

10.5 (8.3;12.8)

19.7 (15.5; 24.5)

High QC

5.3

 

non-AD

57

0.5 (0.4, 0.6)b

7.8 (6.0; 9.5)

30.9 (21.3; 40.7)

Mean

10.5

Ptau231

Total

126

7.3 (6.8, 7.8)

7.8 (6.6; 9.1)

17.4 (14.2; 20.8)

Low QC

15.6

 

AD

71

7.4 (6.9, 7.9)

7.0 (5.6;8.5)

13.4 (10.2; 16.3)

High QC

6.9

 

non-AD

55a

7.2 (6.3, 8.2)

8.8 (6.8; 10.9)

21.7 (15.6; 28.0)

Mean

11.3

T-tau

Total

125

1.53 (1.43, 1.66)

11.1 (9.4; 12.8)

17.7 (14.7; 20.5)

Low QC

9.2

 

AD

68a

1.55 (1.43, 1.66)

9.6 (7.4; 11.6)

17.4 (13.3; 21.7)

High QC

5.1

 

Non-AD

57

1.50 (1.32, 1.68)

12.5 (9.7; 15.5)

18.7 (14.3; 23.2)

Mean

7.2

NfL

Total

128

31.4 (25.61, 37.23)

7.3 (6.2;8.3)

34.1 (27.4; 41.1)

Low QC

3.2

 

AD

71

24.6 (20.1, 29.1)

7.1 (5.5;8.6)

29.6 (21.6; 37.2)

High QC

9

 

non-AD

57

39.9 (28.3, 51.6)

7.5 (5.8;9.2)

39.4 (27.1; 51.1)

Mean

6.1

GFAP

Total

128

128.9 (118.8, 139.0)

11.2 (9.3; 12.9)

20.5 (17.0; 23.8)

Low QC

5.5

 

AD

71

137.3 (123.7, 150.9)

11.4 (9.2; 13.9)

19.6 (15.3; 23.9)

High QC

13.1

 

non-AD

57

118.5 (103.4, 133.6)

10.9 (8.2; 13.5)

21.5 (16.4; 26.6)

Mean

9.3

  1. Table showing the mean concentrations and 95% CI of each biomarker from all three study visits for the total number of participants as well as stratified by a diagnosis of Alzheimer’s disease or other cognitive dementia diseases. Number of samples available for analyses are also presented. Intra- and inter-individual variability for each biomarker is presented together with the corresponding assay variability
  2. Blood samples from two patients obtained at V1 were lost due to technical issues before freezing. CSF was available for those two patients. CSF from 42 patients were available for analyses collected at V1. For 5 patients there was not sufficient CSF for study analyses. In total, 38 patients had a complete set of three blood samples, and CSF was available for 33 of these patients
  3. CI confidence interval, CVA Assay variability (mean intermediate precision), Aβ amyloid-β, p-tau phosphorylated tau, NfL neurofilament light, GFAP glial fibrillary acidic protein
  4. N-missing: AD: V1 n = 2, V2 n = 3, V3 n = 5. Non-AD: V1 n = 0, V2 n = 1, V3 n = 2
  5. a < LOQ (under limit of quantification): Plasma p-tau231 < LOQ n = 2 in the non-AD group, plasma T-tau < LOQ n = 3 in the AD group
  6. bLinear mixed models showed significant difference between groups
  7. cNon-overlapping 95% CI
  8. dMean intermediate CVA for the Aβ42/Aβ40 ratio was calculated as the mean across low and high QCs from both Aβ40 and Aβ42
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Alzheimer's Research & Therapy

ISSN: 1758-9193