Smoking duration alone provides stronger risk estimates of chronic obstructive pulmonary disease than pack-years

Surya P Bhatt; Young-il Kim; Kathy F Harrington; John E Hokanson; Sharon M Lutz; Michael H Cho; Dawn L DeMeo; James M Wells; Barry J Make; Stephen I Rennard; George R Washko; Marilyn G Foreman; Donald P Tashkin; Robert A Wise; Mark T Dransfield; William C Bailey; COPDGene Investigators

doi:10.1136/thoraxjnl-2017-210722

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Smoking duration alone provides stronger risk estimates of chronic obstructive pulmonary disease than pack-years

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Smoking duration alone provides stronger risk estimates of chronic obstructive pulmonary disease than pack-years

Surya P Bhatt, Young-il Kim, Kathy F Harrington, John E Hokanson, Sharon M Lutz, Michael H Cho, Dawn L DeMeo, James M Wells, Barry J Make, Stephen I Rennard, …

Thorax, Vol.73(5), pp.414-421

05/2018

DOI: 10.1136/thoraxjnl-2017-210722

PMCID: PMC5903957

PMID: 29326298

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Abstract

BackgroundCigarette smoking is the strongest risk factor for COPD. Smoking burden is frequently measured in pack-years, but the relative contribution of cigarettes smoked per day versus duration towards the development of structural lung disease, airflow obstruction and functional outcomes is not known.MethodsWe analysed cross-sectional data from a large multicentre cohort (COPDGene) of current and former smokers. Primary outcome was airflow obstruction (FEV1/FVC); secondary outcomes included five additional measures of disease: FEV1, CT emphysema, CT gas trapping, functional capacity (6 min walk distance, 6MWD) and respiratory morbidity (St George’s Respiratory Questionnaire, SGRQ). Generalised linear models were estimated to compare the relative contribution of each smoking variable with the outcomes, after adjustment for age, race, sex, body mass index, CT scanner, centre, age of smoking onset and current smoking status. We also estimated adjusted means of each outcome by categories of pack-years and combined groups of categorised smoking duration and cigarettes/day, and estimated linear trends of adjusted means for each outcome by categorised cigarettes/day, smoking duration and pack-years.Results10 187 subjects were included. For FEV1/FVC, standardised beta coefficient for smoking duration was greater than for cigarettes/day and pack-years (P<0.001). After categorisation, there was a linear increase in adjusted means FEV1/FVC with increase in pack-years (regression coefficient β=−0.023±SE0.003; P=0.003) and duration over all ranges of smoking cigarettes/day (β=−0.041±0.004; P<0.001) but a relatively flat slope for cigarettes/day across all ranges of smoking duration (β=−0.009±0.0.009; P=0.34). Strength of association of duration was similarly greater than pack-years for emphysema, gas trapping, FEV1, 6MWD and SGRQ.ConclusionSmoking duration alone provides stronger risk estimates of COPD than the composite index of pack-years.Trial registration numberPost-results; NCT00608764.

Details

Title: Subtitle: Smoking duration alone provides stronger risk estimates of chronic obstructive pulmonary disease than pack-years
Creators: Surya P Bhatt - UAB Lung Health Center, University of Alabama at Birmingham, Birmingham, Alabama, USA
Young-il Kim - Division of Preventive Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA
Kathy F Harrington - Division of Pulmonary, Allergy and Critical Care Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA
John E Hokanson - Department of Biostatistics and Bioinformatics, National Jewish Health, Denver, Colorado, USA
Sharon M Lutz - Department of Biostatistics and Bioinformatics, National Jewish Health, Denver, Colorado, USA
Michael H Cho - Channing Division of Network Medicine, Brigham and Women’s Hospital, Boston, Massachusetts, USA
Dawn L DeMeo - Pulmonary and Critical Care Medicine, Harvard Medical School, Boston, Massachusetts, USA
James M Wells - UAB Lung Health Center, University of Alabama at Birmingham, Birmingham, Alabama, USA
Barry J Make - Division of Pulmonary, Critical Care and Sleep Medicine, National Jewish Health, Denver, Colorado, USA
Stephen I Rennard - Clinical Discovery Unit, AstraZeneca, Cambridge, UK
George R Washko - Pulmonary and Critical Care Medicine, Harvard Medical School, Boston, Massachusetts, USA
Marilyn G Foreman - Division of Pulmonary and Critical Care Medicine, Morehouse School of Medicine, Atlanta, Georgia, USA
Donald P Tashkin - Division of Pulmonary and Critical Care Medicine, University of California Los Angeles, Los Angeles, California, USA
Robert A Wise - Division of Pulmonary and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
Mark T Dransfield - Pulmonary and Critical Care Medicine, Birmingham VA Medical Center, Birmingham, Alabama, USA
William C Bailey - UAB Lung Health Center, University of Alabama at Birmingham, Birmingham, Alabama, USA
COPDGene Investigators
Contributors: Eric A Hoffman (Contributor) - University of Iowa, Radiology
Resource Type: Journal article
Publication Details: Thorax, Vol.73(5), pp.414-421
DOI: 10.1136/thoraxjnl-2017-210722
PMID: 29326298
PMCID: PMC5903957
ISSN: 0040-6376
eISSN: 1468-3296
Grant note: DOI: 10.13039/100000050, name: National Heart, Lung, and Blood Institute
Language: English
Date published: 05/2018
Academic Unit: Roy J. Carver Department of Biomedical Engineering; Radiology; Internal Medicine
Record Identifier: 9984051590102771

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