NEUROPATHIC PAIN SECTION: High-Dose Intravenous Immunoglobulin Is Effective in Painful Diabetic Polyneuropathy Resistant to Conventional Treatments. Results of a Double-Blind, Randomized, Placebo-Controlled, Multicenter Trial

Objectives. The efficacy and safety of high-dose intravenous immunoglobulin (IVIG) in treatment-resistant diabetic painful polyneuropathy (DPN) were assessed. Design. This was a randomized, double-blind, placebo-controlled, multicenter trial (EudraCT 2010-023883-42). Setting. This trial was conducted at eight sites in Italy with a neurology specialist level of care. Subjects. Twenty-six diabetic patients with DPN who reported baseline severity of pain >60 units (mm) on a VAS scale at enrollment and were resistant to antidepressants and antiepileptic drugs were enrolled; 23 were randomized (11 in the IVIG arm and 12 in the placebo arm). All patients completed the study and were evaluated. All patients were Caucasian, 15were male, and 21 had a diagnosis of type II diabetes. Methods. IVIG (0.4g/kg/d) or placebo was given for five consecutive days. Pain intensity (visual analog scale, Neuropathic Pain Symptom Inventory) and quality of life (36-Item Short-Form Health Survey, Clinical/Patient Global Impression of Change questionnaires) assessments were performed at visits: baseline, start of therapy (one week later), end of therapy (five days later), and follow-up (four and eight weeks later). Results. The study achieved its prespecified primary end point of >50% pain reduction at fourweeks after IVIG, achieved in seven of 11 patients (63.6%) in the IVIG group vs zero of 12 in the placebo group (P = 0.0013). Only two adverse events were reported during the study: one patient in the treatment arm reported a mild "dermatitis psoriasiform," whereas one patient from the placebo group reported a mild "influenza." Conclusions. Treatment with IVIG at the dose given was efficacious and safe for patients with DPN resistant to standard therapies. Key Words: Intravenous Immunoglobulin; Diabetic Painful Polyneuropathy; Clinical Trial; Visual Analog Scale (VAS); Neuropathic Pain Symptom Inventory (NPSI)