IVIg Treatment-Related Fluctuations in CIDP Patients Using Daily Grip Strength Measurements

Subjects will be recruited by individual site investigators. Prior to enrollment each potential subject will have their screening data reviewed by a panel of medical experts for confirmation of inclusion criteria. Each reviewer will be an independent, board-certified, practicing and experienced neurologist with a special interest in CIDP. Enrolled subjects who have provided informed consent will be instructed to perform and document daily Jamar hand-held Dynamometer grip strength measurements in a paper diary for a 6 month time frame. Weekly nursing visits will capture disability assessments, physical tests, adverse event and concomitant medications assessment, and other clinical changes that may affect grip strength measurements. Nurses will review each subjects captured grip data from paper diary on an iPad during weekly home assessments. Nurses will also administer the HRQOL Short-Form (SF) 36 questionnaire at the baseline, week 12 and week 24 study visits. Serum immunoglobulin G (IgG) levels will be captured by the home study nurse at three time points surrounding IVIg infusions and will be classified as either trough, peak, or mid. Each subject will have serum Ig collected by blood draw for the first 4 IVIg treatment cycles, for a total of 12 blood draws per subject. The "trough" serum IgG level will be collected immediately prior to Ig infusion. The "peak" serum IgG level will be collected 5 minutes post-Ig infusion. The "mid" serum IgG level will be collected two weeks post-Ig infusion. There are currently no known biomarkers that can assist with CIDP diagnosis, prognosis, or treatment optimization. As part of this study, subjects will be required to have additional blood taken and stored for future use. Future use may include the possible discovery of specific biomarkers predicting the response to IVIg or other therapies, optimization of IVIg dosage based on pharmacodynamics, pathogenesis of CIDP, and more effective CIDP diagnostic markers. Blood taken for future use will be obtained with each serum IgG sample. No additional blood draws will be required. Should IVIg therapy be discontinued during the study, daily grip strength measurements will continue to be performed and recorded in the subject diary for up to 30 days or to the end of the study, whichever comes first. Weekly nurse visits with collection of the disability assessments and serum IgG blood draws will continue for up to 4 home nurse visits or until the end of the study, whichever comes first.