Roche Diagnostics · Class II · Cleared Oct 8, 2025
| K-number | K252163 |
| Device name | Elecsys Phospho-Tau (181P) Plasma |
| Applicant | Roche Diagnostics |
| Product code | SET |
| Device class | Class II |
| Decision date | Oct 8, 2025 |
| Decision | Substantially Equivalent |
| Regulation | 866.5840 |
The Elecsys Phospho-Tau (181P) Plasma is an in vitro electrochemiluminescence immunoassay that measures phosphorylated Tau 181 protein in human plasma. It is intended as an aid in the initial assessment for Alzheimer's disease and other causes of cognitive decline in adults aged 55 and older presenting with cognitive symptoms, used to help determine whether amyloid pathology is present.
The candidate device measures phosphorylated Tau 181 in plasma samples using a sandwich immunoassay with monoclonal antibodies and chemiluminescence detection, similar to the predicate device which measures the same analyte in cerebrospinal fluid. Both use a single predefined cutoff value (0.722 pg/mL) to classify amyloid PET status as positive or negative.
Testing followed CLSI guidelines: EP05-A3 (precision/reproducibility), EP17-A2 (limit of blank/detection/quantitation), EP06-Ed2 (linearity), EP28-A3c (reference interval), and EP35 (matrix comparison).
The Elecsys Phospho-Tau (181P) Plasma is substantially equivalent to predicate device K221842 because both measure phosphorylated Tau 181 protein and are intended to aid in assessment of cognitive decline patients. The candidate demonstrates substantially equivalent rule-out performance with a positive percent agreement of 92.7% and negative predictive value of 97.9% compared to amyloid PET imaging, establishing comparable clinical utility.
View the full FDA submission: accessdata.fda.gov