High tobacco consumption is causally associated with increased all-cause mortality in a general population sample of 55 568 individuals, but not with short telomeres: a Mendelian randomization study

TY - JOUR

T1 - High tobacco consumption is causally associated with increased all-cause mortality in a general population sample of 55 568 individuals, but not with short telomeres

T2 - a Mendelian randomization study

AU - Rode, Line

AU - Bojesen, Stig E

AU - Weischer, Maren

AU - Nordestgaard, Børge G

N1 - © The Author 2014; all rights reserved. Published by Oxford University Press on behalf of the International Epidemiological Association.

PY - 2014/8/20

Y1 - 2014/8/20

N2 - Background: High cumulative tobacco consumption is associated with short telomeres and with increased all-cause mortality. We tested the hypothesis that high tobacco consumption is causally associated with short telomeres and with increased all-cause mortality. Methods: We studied 55 568 individuals including 32 823 ever smokers from the Danish general population, of whom 3430 died during 10 years of follow-up. All had telomere length measured, detailed information on smoking history, and CHRNA3 rs1051730 genotype, which is associated with tobacco consumption, determined. In a Mendelian randomization study, we conducted observational, genetic, and mediation analyses. Results: First, tobacco consumption was 21.1 pack-years in non-carriers, 22.8 in heterozygotes and 24.8 in homozygotes (P-trend <0.001). Second, the observational multivariable adjusted hazard ratio for all-cause mortality was 1.12 [95% confidence interval (CI): 1.09, 1.15] per doubling in tobacco consumption. In Mendelian randomization analysis, the hazard ratio was 1.08 (1.02, 1.14) per minor CHRNA3 allele in ever smokers. Third, in observational analysis telomeres shortened with -13 base pairs (-18, -8) per doubling in tobacco consumption. In Mendelian randomization analysis, the estimate was +3 base pairs (-10, +15) per minor CHRNA3 allele. Finally, individuals with the shortest vs longest telomeres had a multivariable adjusted hazard ratio of 1.30 (1.13, 1.50) for all-cause mortality; however, in mediation analysis short telomeres explained only + 0.4% (-3.5%, +4.3%) of the association between high tobacco consumption and increased all-cause mortality. Conclusions: High tobacco consumption is causally associated with increased all-cause mortality. High cumulative tobacco consumption is associated with short telomeres observationally, but there is no clear genetic association.

AB - Background: High cumulative tobacco consumption is associated with short telomeres and with increased all-cause mortality. We tested the hypothesis that high tobacco consumption is causally associated with short telomeres and with increased all-cause mortality. Methods: We studied 55 568 individuals including 32 823 ever smokers from the Danish general population, of whom 3430 died during 10 years of follow-up. All had telomere length measured, detailed information on smoking history, and CHRNA3 rs1051730 genotype, which is associated with tobacco consumption, determined. In a Mendelian randomization study, we conducted observational, genetic, and mediation analyses. Results: First, tobacco consumption was 21.1 pack-years in non-carriers, 22.8 in heterozygotes and 24.8 in homozygotes (P-trend <0.001). Second, the observational multivariable adjusted hazard ratio for all-cause mortality was 1.12 [95% confidence interval (CI): 1.09, 1.15] per doubling in tobacco consumption. In Mendelian randomization analysis, the hazard ratio was 1.08 (1.02, 1.14) per minor CHRNA3 allele in ever smokers. Third, in observational analysis telomeres shortened with -13 base pairs (-18, -8) per doubling in tobacco consumption. In Mendelian randomization analysis, the estimate was +3 base pairs (-10, +15) per minor CHRNA3 allele. Finally, individuals with the shortest vs longest telomeres had a multivariable adjusted hazard ratio of 1.30 (1.13, 1.50) for all-cause mortality; however, in mediation analysis short telomeres explained only + 0.4% (-3.5%, +4.3%) of the association between high tobacco consumption and increased all-cause mortality. Conclusions: High tobacco consumption is causally associated with increased all-cause mortality. High cumulative tobacco consumption is associated with short telomeres observationally, but there is no clear genetic association.

KW - Denmark

KW - Female

KW - Follow-Up Studies

KW - Genotype

KW - Humans

KW - Incidence

KW - Male

KW - Mendelian Randomization Analysis

KW - Mortality

KW - Multivariate Analysis

KW - Polymorphism, Genetic

KW - Risk Factors

KW - Smoking

KW - Telomere

KW - Tobacco Use Disorder

U2 - 10.1093/ije/dyu119

DO - 10.1093/ije/dyu119

M3 - Journal article

C2 - 24906368

SN - 0300-5771

VL - 43

SP - 1473

EP - 1483

JO - International Journal of Epidemiology

JF - International Journal of Epidemiology

IS - 5

ER -