Childhood obstructive sleep apnoea: Covariation is not proof of cause

doi:10.1136/bmj.331.7513.405-a

BMJ 2005;331:405 (13 August), doi:10.1136/bmj.331.7513.405-a

Letter

Childhood obstructive sleep apnoea

Covariation is not proof of cause

The first 150 words of the full text of this article appear below.

EDITOR—Neuropsychological deficits may be more commonamong children with obstructive sleep apnoea but that does notprove how many of these deficits are caused by sleep apnoea.Muscular hypotonia and dyscoordination are common among childrenwith neuropsychiatric disabilities, and can cause snoring andobstructive sleep apnoea. Kotagal cites a study by O'Brien etal, describing 35 children with obstructive sleep apnoea (meanage 6.7 years) and 35 closely matched controls.^1
2

This paper by O'Brien et al does not deal with sleep apnoea²;it shows that children who only snore a lot (without apnoea)have slightly more problems of different kinds even when theauthors beforehand removed all children with attention-deficit/hyperactivitydisorder or hyperactivity from the study.

Urschitz et al found that habitual snoring was significantlyassociated with hyperactive (odds ratio 2.4) and inattentivebehavior (4.0).³ These associations were independent of intermittenthypoxia, which is why I believe . . . [Full text of this article]

Mats Reimer, community paediatrician

Child Clinic, Postbox 9, S-43521 Mölnlycke, Sweden reimer@telia.com