Asthma-COPD Overlap Phenotypes and Smoking :Comparative features of asthma in smoking or non-smoking patients with an incomplete reversibility of airway obstruction

ABSTRACT

The development of COPD features, such as an incomplete reversibility of airway obstruction (IRAO), in smoking or non-smoking asthmatic patients, a condition often named Asthma-COPD Overlap (ACO), has been recognized for decades. However, there is a need to know more about the sub-phenotypes of this condition according to smoking.

This study aimed at comparing the clinical, physiological and inflammatory features of smoking and non-smoking asthmatic patients exhibiting IRAO.

In this cross-sectional study, patients with an IRAO with (ACO, ≥20 pack-years) or without (NS-IRAO, <5 pack-years) significant smoking history completed questionnaires about asthma control (ACQ, score 0–6, 6 = better score) and quality of life (AQLQ, score 1–7, 1 = better score) and performed expiratory flows, lung volume and carbon monoxide diffusion capacity measurements. Blood sampling and induced sputum were obtained for systemic and lower airway inflammation assessment.

A total of 115 asthmatic patients were included (75 ACO: age 61 ± 10 years, 60% women and 40 NS-IRAO: age 64 ± 9 years, 38% women). ACO patients had worse asthma control scores (1.8 ± 0.9 vs 1.4 ± 0.9, P = 0.02) and poorer asthma quality of life (5.3 ± 1.0 vs 5.9 ± 1.0, P = 0.003). In addition, ACO had higher residual volume (145 ± 45 vs 121 ± 29% predicted, P = 0.008) and a lower carbon monoxide diffusing capacity corrected for alveolar volume (90 ± 22 vs 108 ± 20% predicted, P = 0.0008). No significant differences were observed in systemic or lower airway inflammation.

In conclusion, in smokers and non-smokers, the presence of IRAO in asthmatics is associated with different phenotypes that reflect the addition of smoking-induced changes to asthma physiopathology.

KEYWORDS:

• Irreversible airway obstruction
• airway diseases
• lung function
• asthma control
• inflammation

Acknowledgments

The authors thank Serge Simard for performing all statistical analyses, Manon Boisvert, Myriam Nadeau and Justine Veilleux for data entry. Finally, we thank all patients who agreed to participate to the study.

Declaration of interest

LPB considers having no conflict of interest but wishes to declare what can be perceived as potential conflicts of interest. Advisory Boards: GlaxoSmithKline, Novartis. Conferences (honoraria): AstraZeneca, GlaxoSmithKline, Merck, Novartis. Sponsorship for investigator-generated research: AstraZeneca, GlaxoSmithKline, Merck Frosst, Schering. Sponsorship for research funding for participating in multicenter studies: AllerGen, Altair, Amgen, Asmacure, AstraZeneca, Boehringer-Ingelheim, Genentech, GlaxoSmithKline, Novartis, Ono Pharma, Pharmaxis, Schering, Wyeth. Support for the production of educational materials: AstraZeneca, GlaxoSmithKline, Merck Frosst, Boehringer-Ingelheim, Novartis. Organizational: Chair of the Global Initiative for Asthma (GINA) Guidelines Dissemination and Implementation Committee, Knowledge Translation, Education and Prevention Chair in Respiratory and Cardiovascular Health, Vice-President of Interasma (Global Asthma Organization).

MEB, JLD, JM, JL and LB have no conflicts of interest to declare.

FM considers having no conflict of interest but wishes to declare what can be perceived as potential conflicts of interest. Received fees for speaking at conferences sponsored by Boehringer Ingelheim, Novartis and Grifols; research grants for participating in multicentre trials sponsored by GlaxoSmithKline, Boehringer Ingelheim, AstraZeneca, and Novartis; and unrestricted research grants from Boehringer Ingelheim, Novartis, and Grifols. F.M. holds a CIHR/GlaxoSmithKline research chair on COPD.

Authors' contribution

MEB, JLD, FM and LPB contributed to conception and design of the study. JM, JL, LB, FM and LPB contributed to collection of data. MEB, FM and LPB contributed to analysis and interpretation of data. LPB and MEB contributed to writing of the manuscript. All authors reviewed the manuscript and approved its final version. LPB is the guarantor of this study.

Additional information

Funding

This study received a non-restrictive investigator-initiated grant from AstraZeneca Canada Inc.