The genetic component of middle ear disease in the first 5 years of life.

OBJECTIVE To determine the genetic component of time with middle ear effusion (MEE) and episodes of MEE and acute otitis media. DESIGN Prospective twin/triplet cohort. SETTING Research center at a tertiary pediatric hospital. PARTICIPANTS A total of 168 healthy same-sex twin and 7 same-sex triplet sets were recruited by age 2 months. INTERVENTIONS Longitudinal assessment of middle ear status by pneumatic otoscopy and tympanometry at monthly evaluations, and at examinations during upper respiratory tract infections or symptoms of middle ear disease. OUTCOME MEASURES Proportion of time with MEE and episodes of acute otitis media and MEE. RESULTS Of the 140 sets for which zygosity was obtained, 114 were followed up to age 3 years and 83 sets to age 5 years. The heritability estimate for proportion of time with MEE in the first 5 years of life was 0.72 (P<.001). The correlation of proportion of time with MEE between children within a set was significantly higher in monozygotic sets (0.65-0.77) than in dizygotic sets (0.31-0.39) for each year to age 3 years. In the fourth and fifth years of life, the correlations decreased in both monozygotic and dizygotic twin sets. CONCLUSIONS Findings for the first 2 years of follow-up have been previously published and indicate a strong genetic component to the proportion of time with MEE. In the present report, which details the entire 5-year follow-up, the effect of this component appears to attenuate after the third year but its cumulative effect remains significant after 5 years.