Idiopathic chronic inflammatory demyelinating polyneuropathy: an epidemiological study in Italy

Aim: The clinical and epidemiological characteristics of chronic inflammatory demyelinating polyneuropathy (CIDP) in an Italian population were assessed. Subjects and methods: All subjects with a diagnosis of demyelinating neuropathy after 1990 in Piemonte and Valle d’Aosta (4 334 225 inhabitants) were considered. The diagnosis of CIDP was based on the research criteria of the American Academy of Neurology. 165 of 294 patients met the diagnostic criteria. Results: The crude prevalence rate was 3.58/100 000 population (95% CI 3.02 to 4.20). At the prevalence day, 76 (49.0%) cases had definite, 67 (43.2%) probable and 12 (7.7%) possible CIDP; disability was mild in 105 (67.7%) cases, moderate in 32 (20.6%) and severe in 18 (11.6%). The course was remitting–relapsing in 40 cases (25.8%), chronic progressive in 96 (61.9%) and monophasic in 19 (12.3%). Considering the 95 patients whose disorder presented in the period 1995–2001, the mean annual crude incidence rate was 0.36/100 000 population (95% CI 0.29 to 0.44), with a male to female ratio of 2.3:1. 14 cases were affected by diabetes mellitus. In multivariate analysis, factors related to severe disability at the prevalence day were: age>60 years; failure of immunomodulating therapies at the time of diagnosis; worse disability at nadir; and chronic course. Conclusion: Incidence and prevalence rates of CIDP in Italy were higher than those observed in most previous studies. At the prevalence day, more than 80% of cases had a mild or moderate disability, indicating either a good response to immunomodulating therapy or a tendency of CIDP to have a mild course in most cases.