Juvenile Chronic Inflammatory Demyelinating Polyneuropathy Epidemiology in Sardinia, Insular Italy

Background: Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is a rare and disabling immunomediated radiculoneuropathy. Its worldwide epidemiology is heterogeneous and, in adults, CIDP prevalence varies from 0.6 to 9 cases per 100,000 population. Juvenile CIDP (jCIDP) is even rarer, with age-specific prevalence rates varying from 0.23 to 1.26 owing to different diagnostic criteria (American Academy of Neurology [AAN] and European Federation of Neurological Societies/Peripheral Nerve Society [EFNS/PNS]), different age grouping or, genuine differences. Objectives: We assessed jCIDP incidence and prevalence in Sardinia, an area at very-high risk for autoimmune diseases, using comparable methods. Design: The study area was the northern Sardinia, insular Italy, with 491,571 inhabitants and a pediatric population (0-18 years) of 79,086 individuals. Results: On prevalence day (December 31, 2019) the total crude, age-specific prevalence rate were 6.32 per 100,000 according with AAN criteria, 7.58 per 100,000 population with European Neuromuscular Center (ENMC) criteria, and 8.85 per 100,000 population with both 2006 and 2010 EFNS/PNS criteria. Crude mean incidence rate were 0.42 per 100,000 per year with AAN criteria, 0.50 per 100,000 per year with ENMC criteria, and 0.59 per 100,000 per year using 2006 and 2010 EFNS/PNS criteria. Of the eight patients, six had typical CIDP, one had multifocal-acquired demyelinating sensory and motor neuropathy (MADSAM), and one chronic immune sensory polyradiculopathy (CISP). Patient's disability was generally mild. Clinical course was progressive, monophasic, or relapsing. Conclusion: jCIDP prevalence and incidence rates in Sardinia were criteria-dependent, the lowest obtained when using AAN criteria, the highest using the EFNS/PNS. Nonetheless, even with the exclusion of the "possible" category, by using comparable methodology, prevalence rates in Sardinia are considerably higher than the range reported in all previous jCIDP studies.