Blood neurofilament light in remote settings: Alternative protocols to support sample collection in challenging pre‐analytical conditions

INTRODUCTION: This study investigated alternative pre‐analytical handling of blood for neurofilament light (NfL) analysis where resources are limited. METHOD: Plasma NfL was measured with single molecule array after alternative blood processing procedures: dried plasma spots (DPS), dried blood spots (DBS), and delayed 48‐hour centrifugation. These were compared to standardized plasma processing (reference standard [RS]). In a discovery cohort (n = 10) and a confirmatory cohort (n = 21), whole blood was obtained from individuals with unknown clinical etiology. In the confirmatory cohort, delayed centrifugation protocol was paired with either 37°C incubation or sample shaking to test the effect of these parameters. RESULTS: Delayed centrifugation (R(2) = 0.991) and DPS (discovery cohort, R(2 )= 0.954; confirmatory cohort, DPS: R(2) = 0.961) methods were strongly associated with the RS. Delayed centrifugation with higher temperatures (R(2) = 0.995) and shaking (R(2) = 0.975) did not affect this association. DPS (P < 0.001) returned concentrations considerably lower than the RS. DISCUSSION: DPS or delayed centrifugation are viable pre‐analytical procedures for the accurate quantification of plasma NfL.