Background: As blood-based biomarkers become critical to Alzheimer's Disease (AD) clinical testing, establishment of less invasive plasma collection methods are key. We compared the Tasso+ and the TAPII capillary whole blood collection devices to traditional venipuncture for safety and efficacy in our clinic and measured AD biomarkers neurofilament-light (NFL), glial fibrillary acidic protein (GFAP), phosphorylated-tau 217 (ptau217), and amyloid-beta 42/40 ratio (Aβ42/40) in cerebrospinal fluid (CSF), capillary, and venous plasma to assess potential age and cognition related group differences.
Method: Patients seen at the Johns Hopkins Center for CSF Disorders (N = 193) underwent diagnostic lumbar punctures and/or extended lumbar drainage procedures. After CSF and venous plasma was collected, warming packs were held to the patient's upper arm site for 5 minutes before capillary blood was collected via TAPII or Tasso+ device for 5 minutes. Post processing, CSF, venous, and capillary plasma was analyzed using Quanterix SIMOA immunoassays. Clinical Dementia Ratings and Montreal Cognitive Assessment scores were also collected.
Result: 86 TAPII and 121 Tasso+ plasma samples were collected from patients (78 M, 115 F) with mean age 61 years ± 18.3 (range 16-91 years). The mean volume for Tasso+ samples was 294.1uL±127.2 and 266.94uL±18.71 for TAPII though this difference was not statistically significant. Tasso+ devices were 90.3% successful in collecting >50uL whole blood, and TAPII devices were 86% successful. NFL, GFAP, and Aβ42/40 ratio in CSF demonstrated moderate positive correlations with both venous and capillary plasma, although TASSO+ samples showed stronger correlation with venous plasma than TAPII (NFL Tasso r = 0.93, p<0.001, TAP r = 0.85, p<0.001; GFAP Tasso r = 0.9, p<0.001, TAP r = 0.85, p<0.001; Aβ42/40 Tasso r = 0.72, p<0.001, TAP r = 0.86, p<0.001). Ptau217 CSF measurements showed a weaker positive correlation with venous and capillary samples (Venous r = 0.34, p<0.001, Tasso r = 0.19, p = 0.048, TAP 0.05, p = 0.623).
Conclusion: Neurodegenerative biomarkers measured in capillary plasma as collected by the Tasso+ and TAPII correlated well with similar measures obtained from venous plasma. Tasso+ and TAPII devices performed similarly regarding success rate and volume collected.
© 2024 The Alzheimer's Association. Alzheimer's & Dementia published by Wiley Periodicals LLC on behalf of Alzheimer's Association.