Phenotypic comparison between smoking and non-smoking chronic obstructive pulmonary disease

Sundeep S Salvi,Peter J Barnes,Shilpa S Kajale,Kuldeep Mandani,Jyoti Londhe,Vandana Vincent,Louise E Donnelly,Sanjay Juvekar,Arjun Nair,Kanchan Pyasi,Sajid Tambe,Sapna Madas,Bill B Brashier,Sze Mun Mak

doi:10.1186/s12931-020-1310-9

Sundeep S Salvi, Peter J Barnes + Show 12 more

Open Access

https://doi.org/10.1186/s12931-020-1310-9

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Abstract

BackgroundAlthough 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.MethodsTwo 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.ResultsCompared 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.ConclusionsCompared 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.

Highlights

Chronic obstructive pulmonary disease (COPD) among non-smokers (NS-COPD) is common, little is known about this phenotype
The smoking COPD (S-COPD) subjects were exposed to 29.2 ± 22.9 (5.0–87.5) pack-years of smoking (29 out of the 117 subjects had between 5 and 10 pack years of smoking history, had no history of asthma and had spirometrically defined COPD), while the biomass smoke COPD subjects were exposed to 111.1 ± 66.3 (0.0–294) hour-years
As there were no significant differences between the non-smoking COPD (NS-COPD) patients with biomass smoke exposure compared to occupational exposure, these two groups were combined for subsequent analyses

Summary

Introduction

COPD among non-smokers (NS-COPD) is common, little is known about this phenotype. Salvi et al Respiratory Research (2020) 21:50 global COPD burden, most of which occur in high income countries [1]. The remaining 65% of the nonsmoking COPD burden occurs mostly in the low and middle income countries of the world. Exposure to biomass smoke during cooking in poorly ventilated homes, [5,6,7] high levels of ambient air pollution, occupational exposures to dust and gases, ambient ozone exposure, poverty, repeated respiratory tract infections during childhood, poorly-controlled chronic persistent asthma and previous tubercular lung disease are nonsmoking risk factors for COPD [8,9,10]

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