The term sleep disordered breathing refers to a range of conditions that result in abnormal breathing during sleep. The most common is sleep apnoea. Apnoea means a temporary pause in breathing. Although there are other types of apnoea, the term ‘sleep apnoea’ usually referes to obstructive sleep apnoea syndrome (OSAS) in which the individual is briefly unable to breathe due to temporary obstruction of the airways in the throat.
Evidence that active and passive smoking increases the risk of sleep apnoea
- People who smoke are twice as likely to have sleep apnoea
- The risk of sleep apnoea increases when people smoke more cigarettes per day
- Smoking by the mother either during or after pregnancy increases the risk of infants and children developing sleep apnoea within the first 2 years of life
- Further studies are needed to investigate the effect of active and passive smoking on the risk of developing sleep apnoea in adults and children
What evidence was used?
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.
Detailed findings and data
People who smoke are twice as likely to have sleep apnoea when compared to those that do not smoke (pooled relative risk ratio 1.97, 95% confidence interval 1.02 to 3.82). Click here to see a forest plot of the findings – Figure A.
However, data from one further study, which didn’t report numerical results, found smoking was not significantly associated with an increased risk of obstructive sleep apnoea (Stradling 1991).
Men were found to have a similar increased risk of sleep apnoea from smoking (1.5-fold increase) as women (1.5-fold increase) when compared to non-smokers; however, this analysis was only based on data from one study. Click here to see a forest plot of the findings – Figure B.
Number of cigarettes
One of the included studies looked at the effect of intensity of smoking based on the number of cigarettes smoked per day (Wetter 1994). This study found a dose−response relationship where the greatest risk of sleep apnoea was associated with smoking at least 40 cigarettes per day (relative risk ratio 8.38, 95% confidence interval 1.68 to 41.94). However, the impact of smoking on sleep apnoea in those consuming fewer cigarettes per day was inconsistent (less than 20 cigarettes per day: relative risk ratio 4.11, 95% confidence interval 1.41 to 11.99; 20-39 cigarettes per day: relative risk ratio 1.66, 95% confidence interval 0.60 to 4.58).
One study (Kahn 1994) reported that maternal smoking during pregnancy approximately doubles the risk of the infant developing sleep apnoea (age range from 1 day to 29 weeks) (relative risk ratio 1.76, 95% confidence interval 1.17 to 2.64).
Another study (Kukla 2005) reported that maternal smoking after birth significantly increases the risk of developing sleep apnoea in children aged 6-18 months (relative risk ratio 1.25, 95% confidence interval 1.06 to 1.47). Click here to see a forest plot of the findings – Figure C.
The study of Kahn (1994) also reported an increase in sleep apnoea where both parents smoked during pregnancy when compared to only mothers smoking during pregnancy (p=0.007).
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Balkau B, Vol S, Loko S, Andriamboavonjy T, Lantieri O, Gusto G, Meslier N, Racineux J-l, Tichet J, and the Data from an Epidemiologic Study on the Insulin Resistance Syndrome (DESIR) Study Group. High baseline insulin levels associated with 6-year incident observed sleep apnoea. Diabetes Care 2010; 33: 1044-1049.
Khan A, Groswasser J, Sottiaux M, Kelmanson I, Franco P, Rebuffat E, Dramaix M, Wayenberg JL. Prenatal exposure to cigarettes in infants with obstructive sleep apnoea. Pediatrics 1994; 93: 778-783.
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Stradling JR, Crosby JH. Predictors and prevalence of obstructive sleep apnoea and snoring in 1001 middle aged men. Thorax 1991; 46: 85-90.
Wetter DW, Young TB, Bidwell TR, Badr MS, Palta M. Smoking as a risk factor for sleep-disordered breathing. Archives of Internal Medicine 1994; 154: 2219-2224.