AimsTo ascertain the number of paediatric deaths (0–14 years) with an underlying rare disease in the Republic of Ireland between the years 2006–2016, and to analyse bed usage by a paediatric cohort of rare disease inpatients prior to in-hospital death.BackgroundRare diseases are often chronically debilitating and sometimes life-threatening diseases, with the majority (69.9%) of rare diseases being of paediatric onset. The Orphanet database contains information on 6172 unique rare diseases. Under-representation of rare diseases in hospital healthcare coding systems leads to a paucity of rare disease epidemiological data required for healthcare planning. Studies have cited variable incidence rates for rare disease, however the burden of rare diseases to healthcare services still remains unclear. This study represents a thorough effort to identify the percentage of child mortality and paediatric bed usage attributable to rare diseases in the Republic of Ireland, thus addressing a major gap in the rare disease field.MethodsRetrospective analysis of paediatric death registration details for the Republic of Ireland in the 11-year period 2006–2016 from the National Paediatric Mortality Register. Data was subcategorised as Neonatal (0–28 days), Post Neonatal (29 days < 1 year) and older (1–14 years). Bed usage data (ICD-10 code, narrative and usage) of paediatric inpatients who died during hospitalisation from January 2015 to December 2016 was extracted from the National Quality Assurance Improvement System of in-patient data. Orphacodes were assigned to rare disease cases from ICD-10 codes or diagnostic narrative of both datasets.ResultsThere were 4044 deaths registered from 2006–2016, aged < 15 years, of these 2368 (58.6%) had an underlying rare disease. Stratifying by age group; 55.6% (1140/2050) of neonatal deaths had a rare disease, 57.8% (450/778) post-neonatal, and 64% (778/1216) of children aged 1–14 years. Mortality coding using ICD-10 codes identified 42% of rare disease cases with the remainder identified using death certificate narrative records. Rare disease patients occupied 87% of bed days used by children < 15 years who died during hospitalisation from January 2015 to December 2016.ConclusionAdditional routine rare disease coding is necessary to identify rare diseases within Irish healthcare systems to enable better healthcare planning. Rare disease patients are overrepresented in paediatric mortality statistics and in-patient length of stay during hospital admission prior to death.