This study aimed to 'define responder' through the concept of minimum clinically important differences using the individually obtained standard errors (MCID-SE) and a heuristic 'external criterion' responsiveness method in patients with Guillain-Barré syndrome (GBS) and chronic inflammatory demyelinating polyradiculoneuropathy (CIDP). One hundred and fourteen newly diagnosed or relapsing patients (GBS: 55, CIDP: 59) were serially examined (1-year follow-up). The inflammatory Rasch-built overall disability scale (I-RODS), Rasch-transformed MRC sum score (RT-MRC), and Rasch-transformed modified-INCAT-sensory scale (RT-mISS) were assessed. Being-a-responder was defined as having a MCID-SE cut-off ≥1.96. Also, the correlations between patients' scores on each scale and the EuroQoL health-status 'thermometer' (external criterion) were determined (higher correlation indicated better responsiveness). In both diseases, the SEs showed a characteristic 'U'-shaped dynamic pattern across each scales' continuum. The number of patients showing a meaningful change were higher for the I-RODS > RT-MRC > RT-mISS and were in GBS higher than CIDP patients. The MCID-SE concept using Rasch-transformed data demonstrated an individual pattern of 'being-a-responder' in patients with immune-mediated neuropathies, and the findings were validated by the external criterion responsiveness method. The I-RODS showed greater responsiveness compared with the MRC and INCAT-sensory scales, and its use is therefore recommended in future trials in GBS and CIDP.

immune-mediated neuropathies, minimum clinically important difference, outcome measure, Rasch
dx.doi.org/10.1111/jns.12118, hdl.handle.net/1765/86017
Journal of the Peripheral Nervous System
Department of Neurology

Vanhoutte, E.K, Draak, T.H.P, Gorson, K.C, van Nes, S.I, Hoeijmakers, J.G.J, Van Der Pol, W.-L, … Merkies, I.S.J. (2015). Impairment measures versus inflammatory RODS in GBS and CIDP: A responsiveness comparison. Journal of the Peripheral Nervous System, 20(3), 289–295. doi:10.1111/jns.12118