Childhood smoking is an independent risk factor for obstructive airways disease in women
- 1Department of Public Health and Primary Care, Institute of Public Health, Cambridge CB2 2SR, UK
- 2Dunn Human Nutrition Unit, University of Cambridge, Cambridge Institute for Medical Research, Cambridge CB2 2XY, UK
- 3The Respiratory Medicine Unit, University of Cambridge, Cambridge Institute for Medical Research, Cambridge CB2 2XY, UK
- Correspondence to:
Dr B Patel
Department of Public Health and Primary Care, Institute of Public Health, University Forvie Site, Robinson Way, Cambridge CB2 2SR, UK;
- Received 12 May 2003
- Accepted 8 April 2004
Objective: To assess whether starting to smoke in childhood increases the risk of obstructive airways disease (OAD) in adult life.
Methods: A retrospective cohort analysis was undertaken of 12 504 current and ex-smokers in the EPIC-Norfolk cohort. The main exposure was starting to smoke during childhood (age <16 years). Three definitions of OAD were used: doctor diagnosed asthma, doctor diagnosed bronchitis/emphysema, and “any OAD” (doctor diagnosed asthma or bronchitis/emphysema, or taking medication used in the treatment of OAD).
Results: Childhood smokers had significantly more pack years of exposure and poorer lung function than subjects who started to smoke in adulthood (⩾16 years). Compared with starting in adulthood, starting to smoke in childhood was associated with a greater risk of bronchitis/emphysema in female smokers (OR 1.79, 95% CI 1.25 to 2.56) and ex-smokers of both sexes (OR 1.29, 95% CI 1.07 to 1.55 in men and OR 1.40, 95% CI 1.05 to 1.85 in women), and of “any OAD” in female smokers (OR 1.72, 95% CI 1.24 to 2.38) and male and female ex-smokers (OR 1.20, 95% CI 1.03 to 1.40 in men and 1.34, 95% CI 1.07 to 1.57 in women). After adjustment for pack years, childhood smoking was associated with poorer lung function (FEV1 92.3% predicted in adult smokers and 89.5% in childhood smokers, p = 0.03) and a greater risk of bronchitis/emphysema (adjusted OR 1.55, 95% CI 1.08 to 2.24) and for “any OAD” (OR 1.54, 95% CI 1.10 to 2.13) in female smokers but not in male and female ex-smokers.
Conclusion: Starting to smoke in childhood is associated with an increased risk of airways disease because of the extra pack years smoked. In women, childhood smoking is itself an independent risk factor for the development of airways disease.
Bipen Patel is funded by a grant from the NHS Executive Anglia and Oxford R&D
EPIC-Norfolk is supported by grant funding from the Cancer Research Campaign, the Medical Research Council, the Stroke Association, the British Heart Foundation, the Department of Health, the Europe Against Cancer Programme Commission of the European Union, and the Ministry of Agriculture, Fisheries and Food.