title: Smoking, second-hand smoke exposure and smoking cessation in relation to leukocyte telomere length and mortality.
abstract: To investigate the link between smoking exposure, telomere length and mortality, with emphasis on second-hand smoke (SHS) exposure and the duration of smoking cessation.
  
  
  
  A total of 1,018 participants died during follow-up (mean: 10.3 years). A 50 base-pair decrease in LTL was shown among cotinine-confirmed current versus never smokers. The 90th quantile of LTL decreased with increasing cotinine among never smokers, indicating a role of SHS. Longer telomeres with smoking cessation were indicated but limited to a 3-16 year period of abstaining smoking. When assessing mortality, we observed a lower risk of all-cause death for the second quintile compared to the first among never smokers (HR: 0.67, 95% CI: 0.52-0.87), and a higher risk was found among current smokers (HR: 1.89, 1.19-2.92).
  
  
  
  We studied 6,456 nationally representative U.S. respondents with mortality follow-up through to 31 December 2011. Smoking status was assessed by interviews and cotinine levels. Relative leukocyte telomere length (LTL) was quantified by polymerase chain reaction (PCR). Multivariable linear regression was performed to examine LTL by smoking exposure, adjusted for age, sex, race/ethnicity, socioeconomic status, education, body mass index, alcohol consumption, and physical activity. We further estimated the association of LTL with cotinine levels using quantile regression, and with smoking cessation dynamics. Cox regression was used to estimate mortality by smoking status and LTL.
  
  
  
  Our findings indicated a complex association between smoking, telomere length, and mortality. LTL alterations with SHS and smoking cessation warrant further investigation for translation to public health measures.
authors: Division of Cancer Studies, King's College London, London, UK.|MRC Unit for Lifelong Health and Ageing, University College London, London, UK.|Division of Haematology/Oncology, Faculty of Medicine, Universitas Gadjah Mada, Yogyakarta, Indonesia.|PILAR Research and Education, Cambridge, UK.
authors: Wahyu
authors: W
authors: Wulaningsih
authors: National Institute of Molecular Biology and Biotechnology, University of The Philippines Diliman, Diliman, Quezon City, Metro Manila, The Philippines.
authors: Fidel Emmanuel C
authors: FE
authors: Serrano
authors: Department of Health Policy and Management, Faculty of Medicine, Universitas Gadjah Mada, Yogyakarta, Indonesia.
authors: Adi
authors: A
authors: Utarini
authors: Department of Biochemistry and Biophysics, University of California, San Francisco, CA, USA.|Driver Group, L.L.C., San Francisco, CA, USA.
authors: Tetsuya
authors: T
authors: Matsuguchi
authors: PILAR Research and Education, Cambridge, UK.|Institute for Mathematical and Molecular Biomedicine, King's College London, London, UK.
authors: Johnathan
authors: J
authors: Watkins
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019588:Aging, Premature / Q000453:epidemiology* / Q000401:mortality; D000073865:Cigarette Smoking / Q000453:epidemiology* / Q000235:genetics; D004781:Environmental Exposure / Q000009:adverse effects; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007962:Leukocytes / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D016540:Smoking Cessation; D016019:Survival Analysis; D059505:Telomere Homeostasis; D014028:Tobacco Smoke Pollution / Q000706:statistics & numerical data*; D006113:United Kingdom / Q000453:epidemiology; D055815:Young Adult
chemical_list: D014028:Tobacco Smoke Pollution
keywords: ageing; second-hand smoke exposure; smoking; smoking cessation; telomere