Aims : to estimate the contribution of rare diseases (RD) among severe impairments in school_age children.
Method : Data from a morbidity register of childhood impairments were used. Impairments were classified as Mental, Sensorial, Neuromuscular, skeletal and movement related impairments (MSN_I) according to the ICF chapter's of body function. Children born from 1980 to 1994, and resident in our county when they were seven-year-old, were actively recorded. Rare diseases were defined by a prevalence rate below 1 per 2000.
Results : Twenty six percent of children with severe MSN_I pertain to the rare diseases group (RD group) whilst 36 % remained of unknown origin. The proportion of RD varies according to type of impairment: 3.3% in children with severe psychiatric disorders; 16.0% for intellectual impairment; 37.2% for hearing impairment; 41.2 for Neuromuscular Skeletal and Movement impairment and 81.1% for visual impairment. Overall prevalence rate of this RD group was 2.1 per 1000 (459/218 283), and it increased significantly over time (p=0.003). This increase was not associated with a decrease in the proportion of unknown origin group, thus it is rather in favour of an improvement in the survival of these children.
Conclusion: Rare diseases are at the origin of 26% of severe MSN_I in children and their prevalence rate is increasing over time.
- childhood disability
- neuro-sensorial deficiency
- rare diseases