Use of individual measure and Z-scores to monitor disease course in Relapsing Multiple Sclerosis: A 1-year Prospective Study in a Single Center
Luis Rafael Solís-Tarazona1, Salma Reddam2, Sara Gil-Perotín1
1Hospital Universitario y Politécnico La Fe, Neuroinmunología, Valencia, Spain, 2Instituto de Investigación Sanitaria La Fe, Laboratorio de Neuroinmunología Dr. Coret, Valencia, Spain
Objective:
To assess the performance of individual serum neurofilament (sNFL) values vs. Z-score to monitor inflammation in persons with relapsing forms of MS (pwRMS)
Background:
Population-based standards of sNFL levels have been recently proposed to detect activity in pwRMS. However, sNFL levels are variable, and the exact algorithm to diagnose individual-based disease activity is not defined yet.
Design/Methods:
A prospective cohort of 114 pwRMS were followed for 1 year. Clinical examination and sNFL assessment were performed and registered every three months. MRIs were performed annually. Baseline sNFL was the sNFL level measured at study inclusion in the absence of disease activity. Reference sNFL level was the lowest individual sNFL measure obtained during follow-up in the absence of disease activity. BMI-adjusted Z-score was registered for baseline, reference, and activity points. Non-parametric tests were used because data did not follow a normal distribution.
Results:
Median baseline sNFL levels were 6.85 (5.15 – 9.09); Z score 0.64 (-0.33 – 1.49). Median reference sNFL levels were 4.71 (4 – 5.87); Z score -0.36 (-1.13 – 0.42). Twenty-four patients (21.1%) had disease activity during follow-up. Median sNFL in these patients was 8.67 pg/ml (6.91 – 13) with an increase of 14.7% over the baseline level: 1.01 (-0.71 – 2.67; P = 0.66) and of 77% over the reference level: 3.63 (2.09 – 6.25; P = 0.001). Z-score during disease activity was 1.13 (0.45 – 2.27), overlapping with control levels in the population-based normogram. In our cohort, none of the individual sNFL measures or baseline Z-score predicted disease activity during the first year of follow-up, but patients with relapse at inclusion were more prone to have disease activity.
Conclusions:
Establishment of an individual sNFL reference value in the first year of follow-up might help to better diagnose ongoing inflammation. Baseline sNFL was not as good comparator for this outcome.