Estimated population prevalence of obstructive sleep apnoea in a community of German third graders

To the Editors:

We read with interest the article by Urschitz et al. 1 which estimated the population prevalence of obstructive sleep apnoea (OSA) in an urban community of German third graders. This article highlights the fact that OSA is one of the most common chronic respiratory diseases in childhood and requires more attention from paediatric health services and clinicians. However, we are concerned that the methods employed in the study to diagnose OSA were suboptimal.

The authors correctly state that full sleep laboratory based polysomnography is the gold standard for the diagnosis of OSA in children. However, for the purposes of their study, abbreviated home polysomnography (HPSG) without electroencephalography was utilised for a final diagnosis of OSA. This was not referenced to the gold standard in this study.

The most recent American Academy of Sleep Medicine manual on scoring of sleep and sleep-related events emphasises the need to record and score not only respiratory events, but also arousals throughout a polysomnography 2. The manual states that if hypopnoeas are to be scored (and form part of the apnoea/hypopnoea index), they must be followed by either arousal or desaturation. The abbreviated HPSG used in this study does not have the ability to detect respiratory events that lead to arousal. On this basis, we feel that the authors may have underestimated the prevalence of OSA in their study population.

• ©2011 ERS