Understanding the consequences of chronic inflammatory demyelinating polyradiculoneuropathy from impairments to activity and participation restrictions and reduced quality of life: The ICE study
A randomized trial (ICE trial) in chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) demonstrated significantly more improvement with intravenous immunoglobulin (Gamunex(®), Talecris Biotherapeutics, Inc., Research Triangle Park, NC) than placebo. To understand the relationship between CIDP impairments, activity and participation restrictions, and quality of life (QoL) in this trial, we investigated the association between scales representing these outcome levels. Gamunex or placebo was given every 3 weeks for up to 24 weeks to 117 patients in an initial treatment period after which treatment failures were crossed over (alternative treatment). We assessed impairments, activity and participation, and SF-36 component mental (MCS) and physical summaries (PCS). Regression analyses of baseline data were performed (all subjects) and change from baseline to endpoint (Gamunex-treated group only) to determine correlations between outcomes. Grip strength, medical research council (MRC) sum score, and inflammatory neuropathy cause and treatment (INCAT) sensory sum score were the strongest explanatory variables of disability (at baseline: r(2) = 0.46; change from baseline: r(2) = 0.66). Only up to half of the variance in QoL scores (PCS at baseline: r(2) = 0.30; change from baseline: r(2) = 0.41; MCS: at baseline: r(2) = 0.10; change from baseline: r(2) = 0.24) was explained by impairment and activity and participation measures. Future studies are required to elucidate the impact of CIDP on disability and QoL changes, because the obtained correlations provide only partial explanation.