Prevalence of chronic inflammatory demyelinating polyneuropathy and multifocal motor neuropathy in two regions of Australia

INTRODUCTION/AIMS: Immune‐mediated neuropathies such as chronic inflammatory demyelinating polyneuropathy (CIDP) and multifocal motor neuropathy (MMN) produce significant disability and often require maintenance treatment. There is a paucity of epidemiological data on these conditions in Australia. METHODS: We undertook a prevalence study of CIDP and MMN in North Queensland and Tasmania, coinciding with a national census. Diagnoses were classified against the diagnostic criteria of the European Federation of Neurological Societies/Peripheral Nerve Society. Case ascertainment was undertaken via multiple methods, including survey of local neurologists across public and private clinics, search of neurophysiology, neurology and hospital databases, search of admitted hospital database collections using ICD codes and through immunoglobulin therapy prescription lists. RESULTS: The crude prevalence of CIDP was 5.00 per 100,000 (95% confidence interval [CI] 3.79–6.62) and the crude prevalence of MMN was 1.33 per 100,000 (95% CI 0.78–2.27). Prevalence was also investigated using National Blood Authority numbers of cases prescribed immunoglobulin therapy, indicating a CIDP prevalence of 5.72 per 100,000 (95% CI 4.41–7.43) and MMN prevalence of 1.94 per 100,000 (95% CI 1.24–3.03). There was no significant difference between these numbers and those calculated through access of patient records locally. There was no significant difference in prevalence between Tasmania and North Queensland for any category. DISCUSSION: This study updates the prevalence of CIDP and MMN in Australia. Understanding the distribution of CIDP and MMN patients and their need for treatment is essential for future resource planning and to enable monitoring and coordination of therapies such as immunoglobulin.