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Table 3 Clinical accuracy: estimated sensitivities and cutoff values at a fixed specificity of 90 % or 95 % (EUROIMMUN assay)

From: Diagnostic value of cerebrospinal fluid Aβ ratios in preclinical Alzheimer’s disease

  Sensitivity (%) 95 % CI Cutoff value Differencea (%) P valueb Correctly classifiedc (%)
Specificity of 90 %       
 Aβ38 14.29 0.00–71.43 1446 65.79 <0.0001 79
 Aβ40 14.29 0.00–71.43 5602 65.79 <0.0001 76
 Aβ42 57.14 0.00–100.00 546 21.05 0.008 84
 ttau 57.14 14.29–100.00 471 10.53 0.125 82
 Aβ42/Aβ38 71.43 0.00–100.00 0.268 7.89 0.250 87
 Aβ42/Aβ40 85.71 14.29–100.00 0.074 10.53 0.125 89
 Aβ42/ttau 85.71 14.29–100.00 1.852 5.26 0.500 89
Specificity of 95 %       
 Aβ38 14.29 0.00–71.43 1342 68.42 <0.0001 82
 Aβ40 14.29 0.00–71.43 5254 71.05 <0.0001 82
 Aβ42 42.86 0.00–85.71 493 28.95 0.001 87
 ttau 42.86 0.00–85.71 539 18.42 0.016 84
 Aβ42/Aβ38 28.57 0.00–71.43 0.251 21.05 0.008 84
 Aβ42/Aβ40 57.14 8.62–85.71 0.067 21.05 0.008 89
 Aβ42/ttau 71.43 28.57–100.00 1.415 13.16 0.063 92
  1. Analyte concentrations are described as pg/ml or calculated as ratios between concentrations of two analytes
  2. aPercentage of subjects who were classified differently based on the cutoff values from fixed specificities compared with the cutoff values corresponding to the highest Youden index (Table 2)
  3. bSignificance for the “Difference”cPercentage of positively classified cases based on the CSF cutoffs from fixed specificities compared with amyloid PET classification
  4. amyloid beta, CI confidence interval, ttau total tau