This is a randomized controlled study evaluating safety and efficacy of repeated immunoadsorption versus immunoglobulins in steroid-refractory Chronic Inflammatory Demyelinating Polyneuropathy (CIDP).

Inclusion Criteria:

• Diagnosis of possible, probable, or definite CIDP (typical or atypical) according to European Federation of Neurological Societies (EFNS) guidelines
• Disease duration of 3 years or less
• Age 18 years or above
• Previous treatment with methyl-prednisolone and insufficient therapeutic response as judged by the treating physician, or contraindications against methyl-prednisolone, or clinically significant side effects under methyl-prednisolone therapy as judged by the treating physician

Exclusion Criteria:

• Clinical or laboratory evidence of manifest systemic infection, i.e., C-reactive protein (CRP) above 20 mg/l, or evidence of nitrite-positive urinary tract infection
• Intake of angiotensin converting enzyme inhibitor within 1 week before first treatment
• immunoglobulin A deficiency
• Other contraindications against immunoadsorption or intravenous immunoglobulins

Individual participant data that underlie the results reported in this article, after de-identification (text, tables, and figures), as well as the study protocol will be available. Data will be available beginning 3 months and ending 5 years following article publication. Data will be shared with researchers who provide a methodologically sound proposal. Data will be shared for analyses to achieve the aims in the approved proposal. Proposals should be directed to johannes.dorst@uni-ulm.de; to gain access, data requestors will need to sign a data access agreement. Data are available for 5 years at https://www.uniklinik-ulm.de/neurologie.html.

3 months after publication until 5 years after publication

Data will be shared with researchers who provide a methodologically sound proposal. Data will be shared for analyses to achieve the aims in the approved proposal.