Connecting impairment, disability, and handicap in immune mediated polyneuropathies

Background: In the World Health Organisation (WHO) International Classification of Impairments, Disabilities, and Handicaps (ICIDH), it is suggested that various levels of outcome are associated with one another. However, the ICIDH has been criticised on the grounds that it only represents a general, non-specific relation between its entities. Objective: To examine the significance of the ICIDH in immune mediated polyneuropathies. Methods: Four impairment measures (fatigue severity scale, MRC sum score, "INCAT" sensory sum score, grip strength with the Vigorimeter), five disability scales (nine hole peg test, 10 metres walking test, an overall disability sum score (ODSS), Hughes functional grading scale, Rankin scale), and a handicap scale (Rotterdam nine items handicap scale (RIH59)) were assessed in 113 clinically stable patients (83 with Guillain-Barre syndrome, 22 with chronic inflammatory demyelinating polyneuropathy, eight with a gammopathy related polyneuropathy). Regression analyses with backward and forward stepwise strategies were undertaken to determine the correlation between the various levels of outcome (impairment on disability, impairment on handicap, disability leading to handicap, and impairment plus disability on handicap). Results: Impairment measures explained a substantial part of disability (R-2 = 0.64) and about half of the variance in handicap (R-2 = 0.52). Disability measures showed a stronger association with handicap (R-2 = 0.76). Combining impairment and disability scales accounted for 77% of the variance in handicap (RIHS9) scores. Conclusions: In contrast to some suggestions, support for the ICIDH model is found in the current study because significant associations were shown between its various levels in patients with immune mediated polyneuropothies. Further studies are required to examine other possible contributors to deficits in daily life and social functioning in these conditions.