A method to study the effect of bronchodilators on smoke retention in COPD patients: study protocol for a randomized controlled trial

The acute effect of cigarette smoking on the high-sensitivity CRP and fibrinogen biomarkers in chronic obstructive pulmonary disease patients

Aim: The evidence on the acute effects of smoking on biomarkers is limited. Our aim was to study the acute effect of smoking on disease-related biomarkers. Methods: The acute effect of smoking on serum high sensitivity CRP (hs-CRP) and plasma fibrinogen and its association with disease severity was studied by challenging 31 chronic obstructive pulmonary disease patients with cigarette smoking and repeatedly measuring these biomarkers before and after smoking. Results: Fibrinogen and hs-CRP increased directly after smoking by 9.4 mg/dl (95% CI: 4.2–14.5) and 0.13 mg/l (95% CI: 0.03–0.23), respectively. Fibrinogen levels remained elevated after 35 min, whereas hs-CRP normalized. Pearson’s correlation coefficient between the hs-CRP change and chronic obstructive pulmonary disease severity was 0.25 (p = 0.06). Conclusion: Fibrinogen and hs-CRP increased directly after smoking in the chronic obstructive pulmonary disease patients. Their association with disease risk and/or progression remains to be demonstrated.

Cigarette smoke retention and bronchodilation in patients with COPD. A controlled randomized trial

INTRODUCTION

Bronchodilators are the cornerstone for symptomatic treatment of chronic obstructive pulmonary disease (COPD). Many patients use these agents while persisting in their habit of cigarette smoking. We hypothesized that bronchodilators increase pulmonary retention of cigarette smoke and hence the risk of smoking-related (cardiovascular) disease. Our aim was to investigate if bronchodilation causes increased pulmonary retention of cigarette smoke in patients with COPD.

METHODS

A double-blinded, placebo-controlled, randomized crossover trial, in which COPD patients smoked cigarettes during undilated conditions at one session and maximal bronchodilated conditions at the other session. Co-primary outcomes were pulmonary tar and nicotine retention. We performed a secondary analysis that excludes errors due to possible contamination. Secondary outcomes included the biomarkers C-reactive protein and fibrinogen, and smoke inhalation patterns.

RESULTS

Of 39 randomized patients, 35 patients completed the experiment and were included in the final analysis. Bronchodilation did not significantly increase tar retention (-4.5%, p = 0.20) or nicotine retention (-2.6%, p = 0.11). Secondary analysis revealed a potential reduction of retention due to bronchodilation: tar retention (-3.8%, p = 0.13), and nicotine retention (-3.4%, p = 0.01). Bronchodilation did not modify our secondary outcomes.

CONCLUSIONS

Our results do not support the hypothesis that cigarette tar and nicotine retention in COPD patients is increased by bronchodilation, whereas we observed a possibility towards less retention.

TRIAL REGISTRATION

www.clinicaltrials.gov: NCT00981851.