To compare the diagnostic utility of serum neurofilament light chain (sNfL) measurements using the Single Molecule Array (Simoa) and the Ella microfluid platform in multiple sclerosis (MS) and neurological as well as somatoform disorders.

sNfL measurement has been established as a reliable estimation of neuroaxonal damage with a particular relevance for neuroinflammatory diseases. Among available platforms, Simoa has been hypothesized to be more sensitive to sNfL changes and Ella is characterized by lower costs and faster processing. Hence, a direct comparison of their utility could guide the diagnostic process in the context of neuroinflammatory disorders.

Partial correlations between sNfL and EDSS controlling for age, sex, BMI and renal function were significant for both Simoa (r=0.273, p=0.028) and Ella (r=0.259, p=0.042) but did not differ between the two platforms (z=0.08, p>0.05). ROC analysis revealed similar diagnostic accuracy for both platforms in predicting EDSS ≥ 3 (Simoa AUC=0.751; Ella AUC=0.661; p>0.05), gadolinium-enhancing lesions on MRI (Simoa AUC=0.726; Ella AUC=0.731; p>0.05) and active neuroinflammatory disease course as defined by having at least 1 relapse during the last year (Simoa AUC=0.615; Ella AUC=0.597; p>0.05). Ella exhibited slightly lower diagnostic accuracy compared to Simoa in differentiating between neurological and somatoform diagnosis (Ella AUC=0.668 vs. Simoa AUC=0.742; p=0.025) as well as in contrasting patients with vs. without acute clinical relapse (Ella AUC=0.579 vs. Simoa AUC=0.630, p=0.045).

Ella and Simoa provide comparable diagnostic utility for most of the clinical variables, though Ella seems to be inferior when comparing parameters where higher measurement sensitivity is required.