To review the subtypes, antibodies, alternative treatment and outcome in patients with IVIG refractory CIDP. 

IVIG is frequently the first line of treatment for CIDP patients. However, some patients do no respond well to IVIG and require alternative therapy. 

Retrospective chart review of all CIDP patients seen at OHSU neuromuscular clinic between 2018-2019.

Of the 40 patients studied, 24 (60%) responded to standard IVIG treatment, 15 (38%) did not respond to IVIG treatment, and one lost to follow-up. In the IVIG refractory CIDP group, all but 1 patient did not respond to alternative therapy. Successful alternative therapy was as follow: Steroid (3 IV solumedrol, 1 po prednisone), Plasma exchange (4), IV cyclophosphamide (3), IV Rituximab (3), azathioprine (1), mycophenolate, (1). In IVIG responsive patients 20 had classical CIDP, 2 had distal CIDP (non MAG), and 4 had MADSAM. Whereas in the IVIG refractory group, 8 had classic CIDP, 7 had distal CIDP (non MAG) (p=0.01), 2 had MADSAM. 5 of the IVIG refractory CIDP patients had neurofascin antibodies. After adjusting for age at onset in a logistic regression model, individuals with distal CIDP were 9 times more likely to be refractory to IVIG compared to those without distal CIDP (OR=9.2, 95%CI: 1.5, 56.4, p=0.016). 

Most IVIG refractory CIDP patients respond to alternative therapies (Steroid, PLEX, cyclophosphamide or rituximab). Distal CIDP (non MAG) are more likely not to respond to IVIG but they do respond to alternative therapy. Neurofascin antibodies are found in a minority of IVIG refractory CIDP patients.