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

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

	Sensitivity (%)	95 % CI	Cutoff value	Difference^a (%)	P value^b	Correctly classified^c (%)
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

Analyte concentrations are described as pg/ml or calculated as ratios between concentrations of two analytes
^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)
^bSignificance for the “Difference”^cPercentage of positively classified cases based on the CSF cutoffs from fixed specificities compared with amyloid PET classification
Aβ amyloid beta, CI confidence interval, ttau total tau

ISSN: 1758-9193