The review started in August 2013, and was designed to identify and update previous systematic reviews that have assessed whether active and/or passive smoking increases the risk of sleep apnoea. Only one systematic review was identified assessing the effect of active smoking on sleep apnoea (Lin 2012). No systematic reviews were identified that looked into the effects of passive smoking on sleep apnoea. Therefore, a full search was conducted to update the systematic review of Lin 2012, and also to search for additional primary studies that have investigated the effect of passive smoking on sleep apnoea. A total of five studies were identified to include in this review.
All of the included studies used a prospective cohort design and were conducted in Europe.
Three of the included studies assessed the effect of personal smoking on the development of sleep apnoea in adults; with one of these studies only assessing the effect in men. The remaining two studies assessed the effect of passive smoking on the development of sleep apnoea in neonates and infants.
Studies measured smoking through self-report in all of the included studies.
The methodological quality of the five studies, as judged by the Newcastle-Ottawa scale score, gave an overall median score of 4 (range 3-5). Using the a priori chosen cut off of 7 to indicate high methodological quality, none of the included studies were judged to be of high quality.