[Siblings with pediatric hearing loss. Data on age at diagnosis and degree of hearing loss]

The Deutsches Zentralregister für kindliche Hörstörungen (DZH = German Registry for Hearing Loss in Children) has so far (30.6.2000) entered data records of 4,027 permanently hearing impaired children. These records include data on a total of 151 pairs of siblings. In seven cases a third sibling was registered. An analysis of the data of siblings with different dates of birth shows that the diagnosis for older siblings was delayed 2 years on average compared to the younger siblings (mean 23.6 months, 95% confidence interval 19.3-27.8 months). The degree of hearing loss, which crucially determines the average age at which a child is diagnosed, correlates statistically significantly with pairs of siblings, so that misleading results can be almost totally avoided. In 11 of 17 cases of twins and triplets, the diagnosis was pronounced simultaneously for both siblings; in the remaining 6 cases, one sibling was diagnosed later. It has become apparent that younger siblings of hearing-impaired children profit from the concomitant routine diagnostic investigation of siblings of hearing-impaired children nowadays common in many institutions, but avoidable delays nevertheless still occur, as shown by the data for twins and triplets. Since in approximately 18% of the registered children with one or more siblings one of the brothers or sisters is likewise hearing-impaired, consistent family investigation is recommended.