Very high dose immunoglobulin treatment for chronic inflammatory demyelinating polyneuropathy : a multicentre UK study

Background
Immunoglobulin dosing is individualised in chronic inflammatory demyelinating polyneuropathy (CIDP).

Methods
We retrospectively compared differences in presentation/outcomes/side effects in subjects on very high dose immunoglobulin defined as ≥ 2 g/kg every 3 weeks (‘Group A’) and subjects on ≤ 1 g/kg every 3 weeks (‘Group B’), from 2 UK centres.

Results
One-hundred and eight subjects with CIDP received immunoglobulins. Group A consisted of 12 subjects (11.1%). Mean dose was 2.63 g/kg every 3 weeks (SD: 0.71). Six subjects (50%) had typical CIDP, 3 (25%) had motor CIDP, and 3 (25%) had multifocal CIDP. Group B consisted of 40 subjects (37%) on a mean dose of 0.47 g/kg every 3 weeks (SD: 0.16). Compared to subjects from Group B, subjects from Group A had greater pre-treatment disability (p = 0.029), more common associated autoimmune disease (p = 0.034), worse post-treatment outcome (p = 0.005) and a longer time to maximal improvement (p = 0.041). No differences were found between the two groups for age/gender/weight/acuteness of presentation/side-effects. Occurrence of any side-effect (p = 0.005), and of thromboembolic complication (p = 0.022), were associated with presence of another autoimmune disease.

Conclusions
Very high dose immunoglobulin may be partially effective in a minority of subjects with CIDP. Subjects treated with very high dose immunoglobulin may have greater pre-treatment disability, be more likely to have another autoimmune disease, have worse post-treatment outcomes, and take longer to reach maximal improvement, than subjects on lower doses. Concurrent autoimmune disease may increase immunoglobulin-induced thromboembolic risk. Earlier consideration of alternative therapies may be more appropriate than immunoglobulin dose escalation in subjects with suboptimal immunoglobulin response.