Incidence and pattern of hearing impairment in children with ≤ 800 g birthweight in British Columbia, Canada.

Aim: This study aimed to evaluate changes over time in the characteristics of permanent hearing impairment (HI) in extremely low-birthweight (ELBW ≤800 g) children.

Methods: Data from sequential visits up to 5 years of age assessing hearing and other neurodevelopmental outcomes were extracted from a cohort of ELBW subjects born between 1983 and 2006 at a single Canadian site. Trends in HI incidence, severity and association with other impairments were analysed in three 8-year epochs.

Results: Fifty of 586 ELBW children had a HI. HI rates increased from 5% in epoch 1 to 7% in epoch 2-13% in epoch 3 (p = 0.01). Mild HI decreased from 78% in epoch 1 to 35% in epoch 3 (p = 0.03). Median age at diagnosis decreased from 13 to 8 months. Comorbidities were more common in HI children than non-HI children: cerebral palsy (40% vs 14%, p < 0.0001)), cognitive (38% vs 12%, p < 0.0001) and visual impairments (16% vs 6%, p = 0.009).

Conclusion: The incidence and severity of hearing impairment in a cohort of extremely low-birthweight children increased significantly from 5% to 13% (p = 0.01) over a 24-year period. Comorbidities were common. Potentially modifiable causes are explored.