Sex differences in emphysema and airway disease in smokers.
BACKGROUND
The authors of previous reports have suggested that women are more susceptible to cigarette smoke and to an airway-predominant COPD phenotype rather than an emphysema-predominant COPD phenotype. The purpose of this study was to test for sex differences in COPD phenotypes by using high-resolution CT (HRCT) scanning in male and female smokers with and without COPD.


METHODS
All subjects completed spirometry and answered an epidemiologic respiratory questionnaire. Inspiratory HRCT scans were obtained on 688 smokers enrolled in a family-based study of COPD. Emphysema was assessed by using a density mask with a cutoff of -950 Hounsfield units to calculate the low-attenuation area percentage (LAA%) and by the fractal value D, which is the slope of a power law analysis defining the relationship between the number and size of the emphysematous lesions. Airway wall thickness was assessed by calculating the square root of the airway wall area (SQRTWA) and the percentage of the total airway area taken by the airway wall (WA%) relative to the internal perimeter.


RESULTS
Women had a similar FEV(1) (women, 65.5% +/- 31.9% predicted; men, 62.1% +/- 30.4% predicted; p = 0.16) but fewer pack-years of cigarette smoking (women, 37.8 +/- 19.7 pack-years; men, 47.8 +/- 27.4 pack-years; p < 0.0001). Men had a greater LAA% (24% +/- 12% vs 20% +/- 11%, respectively; p < 0.0001) and larger emphysematous spaces than women, and these differences persisted after adjusting for covariates (weight, pack-years of smoking, current smoking status, center of enrollment, and FEV(1) percent predicted; p = 0.0006). Women had a smaller SQRTWA and WA% after adjusting for covariates (p < 0.0001).


CONCLUSIONS
Male smokers have more emphysema than female smokers, but female smokers do not show increased wall thickness compared with men.
Camp
Pat G
PG
James Hogg iCAPTURE Centre for Cardiovascular and Pulmonary Research, University of British Columbia, Vancouver, BC, Canada. Electronic address: pgcamp@interchange.ubc.ca.
Coxson
Harvey O
HO
James Hogg iCAPTURE Centre for Cardiovascular and Pulmonary Research, University of British Columbia, Vancouver, BC, Canada; Department of Radiology, University of British Columbia, Vancouver, BC, Canada.
Levy
Robert D
RD
Respiratory Division, University of British Columbia, Vancouver, BC, Canada.
Pillai
Sreekumar G
SG
Genetics Research, GlaxoSmithKline, Research Triangle Park, NC.
Anderson
Wayne
W
Genetics Research, GlaxoSmithKline, Research Triangle Park, NC.
Vestbo
Jørgen
J
School of Translational Medicine, University of Manchester, UK; Department of Cardiology and Respiratory Medicine, Hvidovre University Hospital, Hvidovre, Denmark.
Kennedy
Susan M
SM
St. Paul's Hospital, the School of Environmental Health, University of British Columbia, Vancouver, BC, Canada; St. Paul's Hospital, the School of Environmental Health, University of British Columbia, Vancouver, BC, Canada.
Silverman
Edwin K
EK
Channing Laboratory and Pulmonary and Critical Care Division, Brigham and Women's Hospital, Harvard Medical School, Boston, MA.
Lomas
David A
DA
Department of Medicine, University of Cambridge, Cambridge, UK.
Paré
Peter D
PD
James Hogg iCAPTURE Centre for Cardiovascular and Pulmonary Research, University of British Columbia, Vancouver, BC, Canada.
D005260:Female; D005541:Forced Expiratory Volume / Q000502:physiology; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D029424:Pulmonary Disease, Chronic Obstructive / Q000150:complications* / Q000000981:diagnostic imaging / Q000209:etiology*; D011656:Pulmonary Emphysema / Q000000981:diagnostic imaging / Q000453:epidemiology* / Q000503:physiopathology*; D012129:Respiratory Function Tests; D012720:Severity of Illness Index; D012727:Sex Characteristics; D012907:Smoking / Q000009:adverse effects*; D013147:Spirometry; D014057:Tomography, X-Ray Computed