The German study on sleep-disordered breathing in primary school children: epidemiological approach, representativeness of study sample, and preliminary screening results

In order to study the prevalence of habitual snoring (HS), obstructive sleep apnoea (OSA), other aspects of sleep-disordered breathing (SDB), and their determinants, we enrolled a cross-section of children from the population of third graders attending regular primary schools in Hannover, Germany. The recruitment strategy followed a multistage, probability-clustered design. Selected schools were compared with eligible schools regarding the percentage of children with low socio-economic status (SES). The recruitment process was analysed and response proportions calculated. Study subjects were compared with their school enrolment cohort based on anonymous data provided by school authorities. Habitual snoring and OSA were investigated using parental questionnaires and all children underwent nocturnal home pulse oximetry. There was a good overall representativeness of sampled schools with regard to the percentage of children with low SES. In total, 1760 children were contacted and 1144 (65.0%) agreed to participate. The whole process of self-selection of study subjects was not differential by gender. Compared with their school enrolment cohort, study subjects had slightly higher educated parents. The prevalence of HS was estimated to be 10.1%[95% CI 8.3, 11.9%]; and 3.2%[2.2, 4.2%] and 3.9%[2.8, 4.2%] had an abnormally high OSA or SDB score respectively. Based on pulse oximetry, 2.4%[95% CI 1.5, 3.4%] had 3 D(90)and 3 D-C, 1.0%[0.4, 1.6%] had the DI90 > 0.6, and 3.3%[2.2, 4.4%] had the DI4 > 3.9 and the DIC > 0.4. This study sample appears to be highly representative with regard to all available data from the population, and therefore suitable to study the prevalence of HS and OSA. Our prevalence estimates are in the range of other studies.