title: Childhood hearing impairment in northern Finland, etiology and additional disabilities.
abstract: OBJECTIVE
  The purpose of this study was to determine the prevalence and etiology of hearing impairment (HI) in Finnish children and to evaluate the frequency and type of additional disabilities among children with HI.
  
  
  METHODS
  Subjects consisted of 214 children with mild to profound HI ascertained until the age of 10 years. They belonged to the birth cohort spanning the years 1993-2002 in northern Finland. The clinical data were collected from the electronic patient records of the Oulu University Hospital. Age at ascertainment, degree and type of HI and audiogram configuration were determined. Risk factors and etiology of HI and co-existing disabilities were recorded.
  
  
  RESULTS
  The prevalence of childhood HI was 2.3/1000 live births (95% CI; 2.0, 2.7). The etiology of HI was genetic in 47.2%, acquired in 16.4% and unknown in 36.4% children. Among the 214 children with HI, 101 (47.2%) had other minor or major disabilities. The frequency of additional disabilities did not differ between children with mild HI and those with moderate or severe HI (p=0.78). Additional disabilities were more common (65.7%) in children with acquired HI than in children with genetic or unknown HI (43.6%) (p=0.035).
  
  
  CONCLUSIONS
  The prevalence of childhood HI has remained unchanged in northern Finland as compared to previous studies. Genetic causes were the most common (47%) etiology of childhood HI. Among acquired causes of HI, perinatal risk factors were more common than previously. The frequency of additional disabilities was similar among children with different degrees of HI. Because almost 40% of children had one or more additional disabilities affecting development or learning, it is important to take them into consideration in rehabilitation.
authors.affiliation: Department of Otorhinolaryngology, Oulu University Hospital, Oulu, Finland; Medical Research Center, Oulu University Hospital, Oulu, Finland; Institute of Clinical Medicine, Department of Otorhinolaryngology, University of Oulu, Oulu, Finland. Electronic address: sanna.hakli@oulu.fi.
authors.forename: Sanna
authors.initials: S
authors.lastname: Häkli
authors.affiliation: Department of Otorhinolaryngology, Oulu University Hospital, Oulu, Finland.
authors.forename: Mirja
authors.initials: M
authors.lastname: Luotonen
authors.affiliation: Medical Informatics and Statistics Research Group, University of Oulu, Oulu, Finland.
authors.forename: Risto
authors.initials: R
authors.lastname: Bloigu
authors.affiliation: Medical Research Center, Oulu University Hospital, Oulu, Finland; Institute of Clinical Medicine, Department of Neurology, University of Oulu, Oulu, Finland; Department of Neurology, Oulu University Hospital, Oulu, Finland.
authors.forename: Kari
authors.initials: K
authors.lastname: Majamaa
authors.affiliation: Department of Otorhinolaryngology, Oulu University Hospital, Oulu, Finland; Institute of Clinical Medicine, Department of Otorhinolaryngology, University of Oulu, Oulu, Finland.
authors.forename: Martti
authors.initials: M
authors.lastname: Sorri
mesh_terms: D002648:Child; D015331:Cohort Studies; D000013:Congenital Abnormalities / Q000453:epidemiology; D005260:Female; D005387:Finland / Q000453:epidemiology; D034381:Hearing Loss / Q000453:epidemiology* / Q000209:etiology*; D006801:Humans; D008297:Male; D000068079:Motor Disorders / Q000453:epidemiology; D065886:Neurodevelopmental Disorders / Q000453:epidemiology; D015995:Prevalence; D012307:Risk Factors; D012720:Severity of Illness Index; D014786:Vision Disorders / Q000453:epidemiology
keywords: Additional disorder; Comorbidity; Configuration; Hearing loss; Prevalence