Cotinine-assessed second-hand smoke exposure and risk of cardiovascular disease in older adults
OPEN ACCESS- B J Jefferis1,
- D A Lawlor2,
- S Ebrahim3,
- S G Wannamethee1,
- C Feyerabend4,
- M Doig4,
- L McMeekin4,
- D G Cook5,
- P H Whincup5
- 1UCL Department of Primary Care and Population Health, UCL Medical School, London, UK
- 2MRC CAiTE Centre, University of Bristol, Bristol, UK
- 3Non-Communicable Diseases Epidemiology Unit, Department of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, London, UK
- 4ABS Laboratories, BioPark, Welwyn Garden City, UK
- 5Division of Community Health Sciences, St George's, University of London, London, UK
- Correspondence to Dr B J Jefferis, UCL Department of Primary Care and Population Health, UCL Medical School, Rowland Hill Street, London NW3 2PF, UK; b.jefferis{at}ucl.ac.uk
- Accepted 25 March 2010
Abstract
Objectives To examine whether second-hand smoke (SHS) exposure measured by serum cotinine is associated with increased coronary heart disease (CHD) and stroke risk among contemporary older British adults.
Design Prospective population-based study with self-reported medical history and health behaviours. Fasting blood samples were analysed for serum cotinine and cardiovascular disease (CVD) risk markers.
Setting Primary care centres in 25 British towns in 1998–2001.
Patients 8512 60–79-year-old men and women selected from primary care registers.
Main outcome measures Fatal and non-fatal myocardial infarction (MI; n=445) and stroke (n=386) during median 7.8-year follow-up.
Main exposure Observational study of serum cotinine assayed from fasting blood sample using liquid chromatography tandem mass spectrometry method, and self-reported smoking history.
Results Among 5374 non-smokers without pre-existing CVD, geometric mean cotinine was 0.15 ng/ml (IQR 0.05–0.30). Compared with non-smokers with cotinine ≤0.05 ng/ml, higher cotinine levels (0.06–0.19, 0.2–0.7 and 0.71–15.0 ng/ml) showed little association with MI; adjusted HRs were 0.92 (95% CI 0.63 to 1.35), 1.07 (0.73 to 1.55) and 1.09 (0.69 to 1.72), p(trend)=0.69. Equivalent HRs for stroke were 0.82 (0.55 to 1.23), 0.74 (0.48 to 1.13) and 0.69 (0.41 to 1.17), p(trend)=0.065. The adjustment for sociodemographic, behavioural and CVD risk factors had little effect on the results. The HR of MI for smokers (1–9 cigarettes/day) compared with non-smokers with cotinine ≤0.05 ng/ml was 2.14 (1.39 to 3.52) and 1.03 (0.52 to 2.04) for stroke.
Conclusions In contemporary older men and women, SHS exposure (predominantly at low levels) was not related to CHD or stroke risks, but we cannot rule out the possibility of modest effects at higher exposure levels.
- Secondhand smoke
- cotinine
- MI
- stroke
- prospective cohort
- stroke
- smoking
- acute coronary syndrome
- epidemiology
- public health
Footnotes
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Funding This work was supported by the British Heart Foundation: the British Regional Heart Study Research Group is supported by (programme grant RG/04/003). Cotinine analyses were funded by (project grant PG/06/154/22043). The British Women's Heart and Health Study is jointly funded by the UK Department of Health and the British Heart Foundation. The views expressed in this publication are those of the authors and not necessarily those of the funding bodies.
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Competing interests None.
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Ethics approval This study was conducted with the approval of the London Multicentre Research Ethics Committee.
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Provenance and peer review Not commissioned; externally peer reviewed.
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