Objective In daily clinical practice, smokers with asthma and with intermittent disease severity are frequently encountered. The effects of short-term smoking on lung function or disease presentation in younger patients with intermittent adult-onset asthma remain unclear. We sought to clarify the effects of short-term smoking (<10 pack-years) on lung function and airway hyper-responsiveness (AHR) in young patients with untreated intermittent adult-onset asthma.
Design Retrospective, cross-sectional study.
Setting A single primary–tertiary medical centre in Japan.
Participants From patients who underwent bronchodilator reversibility tests between January 2004 and March 2011 (n=7291), 262 consecutive patients (age, 20–34 years) with untreated intermittent adult-onset asthma, including 157 never smokers and 105 current smokers within 10 pack-years, were analysed.
Primary and secondary outcome measures The primary outcome was the association of the daily smoking frequency (number of cigarettes per day), smoking duration (years) and cumulative smoking history (pack-years) with postbronchodilator lung function. The secondary outcome was the association of the former three smoking parameters with AHR.
Results The daily smoking frequency, smoking duration and cumulative smoking history were significantly associated with decreased postbronchodilator lung function. Daily smoking of ≥11 cigarettes per day was also associated with marked AHR (OR 2.23; 95% CI 1.03 to 4.80), even after adjustment for age, sex, disease duration and body mass index.
Conclusion Short-term active smoking in early adulthood may be associated with decreased lung function and AHR, even in patients with intermittent adult-onset asthma. Our findings suggest a benefit of never smoking, even for young patients with intermittent adult-onset asthma.
- airway hyperresponsiveness
- lung function
- young patients
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Contributors MT and KS: conception or design of the study. KS, HH and KW: acquisition, analysis or interpretation of data. KW and YF: drafting the work (writing the manuscript) or revising it critically for important intellectual content. MT: final approval of the version to be published.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests None declared.
Ethics approval The Research Ethics Committee of Sagamihara National Hospital approved the study protocol, which included an opt-out consent policy (No 3 in 2013).
Provenance and peer review Not commissioned; externally peer reviewed.
Data sharing statement No additional data are available.
Patient consent for publication Not required.
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