By Tine Marie Pedersen
Chariman: Preben Homøe
Opponent: Christina West
Opponent: Jørgen Lous
Conductive hearing loss caused by fluid in the middle ear space called middle ear effusion (MEE) is an important concern about otitis media (OM). Prolonged hearing disability in early childhood can affect especially the linguistic and cognitive development .
The most common treatment for recurrent OM and persistent MEE in numerous countries is the insertion of ventilation tubes (VT) in the tympanic membrane. Therefore, we investigated the incidence of VT insertions in Denmark and compared it to other countries. Furthermore, to analyze risk factors of VT in a prospective study cohort, and finally to study the effect of MEE and treatment with VT on the neurological development of the children.
In study I we aimed to investigate the incidence of VT in Denmark using registry data. We compared this to findings in the COPSAC2010 cohort and analyzed determinants of VT insertions using the cohort data. This is a solid outcome compared to former studies using a more unclear and varied definition of OM.
We found an incidence of 35/1000 for all children 0-15 years of age in Denmark. This is to our knowledge the highest in the world. The prevalence of VT was 24% for children 0-3 years of age, which is comparable to the COPSAC2010 cohort where we found a prevalence of 29% before the age of 3. Determinants of VT were older siblings, children also suffering from persistent wheeze and family history of middle ear disease.
In Study II we investigated the relation between maternal antibiotic intake during pregnancy and the children’s risk of acute otitis media (AOM) or VT in early childhood. The consumption of antibiotics is increasing worldwide. A concern is that this may have possible adverse long-term consequences. Antibiotic treatment during pregnancy can alter the maternal bacterial colonization which have raised the hypothesis is that an
inappropriate exposure in pregnancy can initiate a propensity for disease in the child. In the COPSAC2010 cohort 37% of the mothers were treated with antibiotics during pregnancy.
We found that maternal antibiotic intake during pregnancy was significantly associated with increased risk of AOM and VT before the age of 3. Especially treatment late in pregnancy increased the risk of VT; we also observed a dose-response relationship with an increased risk of AOM with increasing number of treatments. The effect late in pregnancy points towards a potential mechanism of altered microbiome.
In Study III we explored the possible association between MEE and the neurological development of children in the COPSAC2010 cohort. We used several developmental endpoints: age at achievement of gross motor milestones, language development at 1 and 2 years of age, cognitive score at 2.5 years and a general development score based on a questionnaire regarding: fine motor, gross motor, problem solving, communication and personal-social skills at 3 years of age.
We found slightly lower language scores for children with MEE in the 1-year language test. Regarding the cognitive scores; we found that children who had had VT inserted scored lower than children with MEE or children without middle ear disease. In conclusion, children with MEE at 1 year had slightly lower language scores at 1-year, but they were not delayed in other ways when examining several neurological endpoints up to the age of 3. Furthermore, our data do not support an effect of treatment with VT on the neurological development.
In conclusion, Denmark has a very high incidence of VT insertions and to our knowledge the highest in the world. From our prospective birth cohort study; we found that older siblings, history of persistent wheeze and family history of otitis media were determinants of VT insertions. We also found that maternal antibiotics during pregnancy increased the risk of OM. Furthermore, we showed that children with MEE are delayed in their early language development, but without a long-lasting effect.