Longitudinal changes in social functioning in mildly disabled patients with relapsing-remitting multiple sclerosis receiving subcutaneous interferon β-1a: results from the COGIMUS (COGnitive Impairment in MUltiple Sclerosis) study (II)

Purpose To report longitudinal changes in and explore the influence of cognition on social functioning in mildly disabled patients with relapsing-remitting multiple sclerosis (RRMS). Methods Italian patients (18-50 years) with RRMS and Expanded Disability Status Scale (EDSS) score <= 4.0 were assigned to interferon beta-1a, 44 or 22 mu g subcutaneously three times weekly, and underwent annual assessments for social functioning (Environmental Status Scale [ESS]) over 3 years. Results Baseline total ESS score did not differ between patients with and without cognitive impairment (P = 0.505). Total ESS score remained low (<2.0) and stable over 3 years in the whole study population, but worsened slightly when assessed by assigned treatment or treatment and baseline cognitive status (both P = 0.004), driven mostly by changes in the 'transportation' and 'financial/economic status' subscales. The strongest independent predictor of worsening ESS score was baseline EDSS score. Test-retest analyses confirmed that total ESS score and most subscales changed little over 3 years. Conclusion ESS scores remained low and changed minimally over 3 years, reflecting the mild physical disability and good cognitive performance in this patient population. Determining the influence of cognitive function and treatment on longitudinal changes in social functioning requires further studies.