Lower-extremity Dynamometry as a Novel Outcome Measure in a Double-blind, Placebo-controlled, Feasibility Trial of Intravenous Immunoglobulin (IVIG) for HIV-associated Myelopathy.

Objective: Open-label data suggest that intravenous immunoglobulin (IVIG) might improve lower-extremity strength in human immunodeficiency virus (HIV)-associated myelopathy (HIVM), a rare but debilitating neurologic complication of HIV. We sought to determine the feasibility of testing the efficacy of IVIG for HIVM more rigorously. Design: We conducted a randomized, double-blind, placebo-controlled feasibility trial of IVIG for HIVM, using dynamometry as an outcome measure (Clinical Trial No. NCT01561755). Setting: The study took place in an academic medical center in New York, New York Participants: Only 12 participants were enrolled in four years; critical impediments to the study were the rarity of patients with new HIVM diagnoses and prior exposure to IVIG in patients with an established diagnosis. Measurements: Dynamometry of hip flexion, knee flexion, and ankle dorsiflexion were measured; the HIV Dementia Motor Score (HDMS); and the two-minute timed walk test were utilized.
Results: Recruitment was the major feasibility issue. Dynamometry was generally well-tolerated, had good test-retest reliability (r=0.71-0.86, p<0.02 for all muscle groups), and good inter-item reliability as judged by the correlations between the muscle groups (r=0.76-0.81, p=0.001-0.005). Dynamometry was valid and clinically meaningful based on its correlations with the HDMS and the two-minute timed walk test.
Conclusion: We conclude that an adequately powered clinical trial of IVIG for HIVM would likely require a prolonged recruitment period and multiple participating sites. Lower limb dynamometry is a useful outcome measure for HIVM, which might also be useful in other HIV-related gait disorders.