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- Cullen, Nicholas C., et al.
(författare)
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Test-retest variability of plasma biomarkers in Alzheimer's disease and its effects on clinical prediction models
- 2023
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Ingår i: Alzheimers & Dementia. - : Wiley. - 1552-5260 .- 1552-5279. ; 19:3, s. 797-806
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Tidskriftsartikel (refereegranskat)abstract
- INTRODUCTION The effect of random error on the performance of blood-based biomarkers for Alzheimer's disease (AD) must be determined before clinical implementation. METHODS We measured test-retest variability of plasma amyloid beta (A beta)42/A beta 40, neurofilament light (NfL), glial fibrillary acidic protein (GFAP), and phosphorylated tau (p-tau)217 and simulated effects of this variability on biomarker performance when predicting either cerebrospinal fluid (CSF) A beta status or conversion to AD dementia in 399 non-demented participants with cognitive symptoms. RESULTS Clinical performance was highest when combining all biomarkers. Among single-biomarkers, p-tau217 performed best. Test-retest variability ranged from 4.1% (A beta 42/A beta 40) to 25% (GFAP). This variability reduced the performance of the biomarkers (approximate to Delta AUC [area under the curve] -1% to -4%) with the least effects on models with p-tau217. The percent of individuals with unstable predicted outcomes was lowest for the multi-biomarker combination (14%). DISCUSSION Clinical prediction models combining plasma biomarkers-particularly p-tau217-exhibit high performance and are less effected by random error. Individuals with unstable predicted outcomes ("gray zone") should be recommended for further tests.
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| 2. |
- Palmqvist, Sebastian, et al.
(författare)
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An accurate fully automated panel of plasma biomarkers for Alzheimer's disease
- 2023
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Ingår i: Alzheimers & Dementia. - : Wiley. - 1552-5260 .- 1552-5279. ; 19:4, s. 1204-1215
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Tidskriftsartikel (refereegranskat)abstract
- Introduction There is a great need for fully automated plasma assays that can measure amyloid beta (A beta) pathology and predict future Alzheimer's disease (AD) dementia. Methods Two cohorts (n = 920) were examined: Panel A+ (n = 32 cognitively unimpaired [CU], n = 106 mild cognitive impairment [MCI], and n = 89 AD) and BioFINDER-1 (n = 461 CU, n = 232 MCI). Plasma A beta 42/A beta 40, phosphorylated tau (p-tau)181, two p-tau217 variants, ApoE4 protein, neurofilament light, and GFAP were measured using Elecsys prototype immunoassays. Results The best biomarker for discriminating A beta-positive versus A beta-negative participants was A beta 42/A beta 40 (are under the curve [AUC] 0.83-0.87). Combining A beta 42/A beta 40, p-tau181, and ApoE4 improved the AUCs significantly (0.90 to 0.93; P< 0.01). Adding additional biomarkers had marginal effects (Delta AUC <= 0.01). In BioFINDER, p-tau181, p-tau217, and ApoE4 predicted AD dementia within 6 years in CU (AUC 0.88) and p-tau181, p-tau217, and A beta 42/A beta 40 in MCI (AUC 0.87). Discussion The high accuracies for A beta pathology and future AD dementia using fully automated instruments are promising for implementing plasma biomarkers in clinical trials and clinical routine.
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| 3. |
- Rabe, C., et al.
(författare)
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Clinical performance and robustness evaluation of plasma amyloid-beta(42/40) prescreening
- 2023
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Ingår i: Alzheimers & Dementia. - : Wiley. - 1552-5260 .- 1552-5279. ; 19:4, s. 1393-1402
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Tidskriftsartikel (refereegranskat)abstract
- Introduction Further evidence is needed to support the use of plasma amyloid beta (A beta) biomarkers as Alzheimer's disease prescreening tools. This study evaluated the clinical performance and robustness of plasma A beta(42)/A beta(40) for amyloid positivity prescreening. Methods Data were collected from 333 BioFINDER and 121 Alzheimer's Disease Neuroimaging Initiative study participants. Risk and predictive values versus percentile of plasma A beta(42)/A beta(40) evaluated the actionability of plasma A beta(42)/A beta(40), and simulations modeled the impact of potential uncertainties and biases. Amyloid PET was the brain amyloidosis reference standard. Results Elecsys plasma A beta(42)/A beta(40) could potentially rule out amyloid pathology in populations with low-to-moderate amyloid positivity prevalence. However, simulations showed small measurement or pre-analytical errors in A beta(42) and/or A beta(40) cause misclassifications, impacting sensitivity or specificity. The minor fold change between amyloid PET positive and negative cases explains the biomarkers low robustness. Discussion Implementing plasma A beta(42)/A beta(40) for routine clinical use may pose significant challenges, with misclassification risks. Highlights Plasma A beta(42)/A beta(40) ruled out amyloid PET positivity in a setting of low amyloid-positive prevalence. Including (pre-) analytical errors or measurement biases caused misclassifications. Plasma A beta(42)/A beta(40) had a low inherent dynamic range, independent of analytical method. Other blood biomarkers may be easier to implement as robust prescreening tools.
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