Phenotypic comparison between smoking and non-smoking chronic obstructive pulmonary disease.
BACKGROUND
Although COPD among non-smokers (NS-COPD) is common, little is known about this phenotype. We compared NS-COPD subjects with smoking COPD (S-COPD) patients in a rural Indian population using a variety of clinical, physiological, radiological, sputum cellular and blood biomarkers.


METHODS
Two hundred ninety subjects (118 healthy, 79 S-COPD, 93 NS-COPD) performed pre- and post-bronchodilator spirometry and were followed for 2 years to study the annual rate of decline in lung function. Body plethysmography, impulse oscillometry, inspiratory-expiratory HRCT, induced sputum cellular profile and blood biomarkers were compared between 49 healthy, 45 S-COPD and 55 NS-COPD subjects using standardized methods. Spirometric response to oral corticosteroids was measured in 30 female NS-COPD patients.


RESULTS
Compared to all male S-COPD subjects, 47% of NS-COPD subjects were female, were younger by 3.2 years, had greater body mass index, a slower rate of decline in lung function (80 vs 130 mL/year), more small airways obstruction measured by impulse oscillometry (p < 0.001), significantly less emphysema (29% vs 11%) on CT scans, lower values in lung diffusion parameters, significantly less neutrophils in induced sputum (p < 0.05) and tended to have more sputum eosinophils. Hemoglobin and red cell volume were higher and serum insulin lower in S-COPD compared to NS-COPD. Spirometric indices, symptoms and quality of life were similar between S-COPD and NS-COPD. There was no improvement in spirometry in NS-COPD patients after 2 weeks of an oral corticosteroid.


CONCLUSIONS
Compared to S-COPD, NS-COPD is seen in younger subjects with equal male-female predominance, is predominantly a small-airway disease phenotype with less emphysema, preserved lung diffusion and a slower rate of decline in lung function.
['Salvi|Sundeep S|SS|', 'Brashier|Bill B|BB|', 'Londhe|Jyoti|J|', 'Pyasi|Kanchan|K|', 'Vincent|Vandana|V|', 'Kajale|Shilpa S|SS|', 'Tambe|Sajid|S|', 'Mandani|Kuldeep|K|', 'Nair|Arjun|A|', 'Mak|Sze Mun|SM|', 'Madas|Sapna|S|', 'Juvekar|Sanjay|S|', 'Donnelly|Louise E|LE|', 'Barnes|Peter J|PJ|http://orcid.org/0000-0002-5122-4018']
D000367:Age Factors D000368:Aged D016022:Case-Control Studies D003430:Cross-Sectional Studies D005260:Female D006801:Humans D008297:Male D008875:Middle Aged D000078405:Non-Smokers D010641:Phenotype D029424:Pulmonary Disease, Chronic Obstructive D012737:Sex Factors D000074285:Smokers D013147:Spirometry D000073869:Tobacco Smoking
Chronic obstructive pulmonary disease biomass smoke household air pollution non-smoking COPD small airway disease