Marieke van Rosmalen

Chapter 2 34 Table 2.2 Outcome measures over time Parameter MD per year 95% CI p ODSS (0 – 12 points) -0.004 0.03 – -0.04 0.81 MRC sum score (0 – 180 points) -1.361 -0.97 – -1.75 < 0.001 SES (0 – 25 points) 0.352 0.54 – 0.16 < 0.001 FSS (0 – 63 points) -0.940 -0.25 – -1.63 < 0.001 Vibration sense (abnormal in 0 – 4 limbs) 0.121 0.15 – 0.09 < 0.001 Reflexes arm (absence in 0 – 4 reflexes) 0.055 -0.02 – -0.09 < 0.001 Reflexes leg (absence in 0 – 4 reflexes) 0.072 -0.03 – -0.11 < 0.001 Reflexes sum score (absence in 0 – 8 reflexes) 0.121 --0.06 – -0.18 < 0.001 Grip strength right (kPa) -1.127 -0.39 – -1.87 < 0.001 Grip strength left (kPa) -0.770 0.04 – -1.58 0.06 Number of affected muscle groups 0.465 0.36 – 0.58 < 0.001 Mean difference per year was calculated as the difference between visit 1 (2007) and visit 2 (2015-2016) divided by the follow-up duration. Absence of reflexes arm: biceps and triceps reflexes (0 – 4). Absence of reflexes leg: knee and ankle reflexes (0 – 4). Abbreviations: MD = mean difference; CI = confidence interval; ODSS = Overall Disability Sum Score; MRC = Medical Research Council; SES = Self-evaluation Scale; FSS = Fatigue Severity Scale. Predictors of progression Multiple linear regression showed that faster progression, i.e. a larger difference of the MRC sum score of visit 1 (2007) and visit 2 (2015 – 2016) per year correlated with the reflexes sum score (i.e. absent reflexes) and a lower MRC sum score in 2007 ( p = 0.016 and p = 0.007 respectively). DISCUSSION This study aimed to document clinical outcomes of patients with MMN and identify predictors of disease progression. We combined cross-sectional data with longitudinal data with a mean duration between visits of eight years. Our clinical observations confirmed that MMN is a progressive disorder in the large majority of patients even when they receive immunoglobulin maintenance treatment. Virtually all selected outcome measures significantly deteriorated over time. Factors with prognostic value of a progressive disease course were absence of reflexes and a lower MRC sum score at baseline. A previous study described the natural history of 38 treatment-naive patients with MMN retrospectively. Patients with longer disease duration (n = 10) had significantly lower MRC sum scores and a higher number of affected regions. None of the patients experienced spontaneous improvement or a relapsing remitting course. 13 Taylor et al. longitudinally assessed 18 patients