Early COPD patients with lung hyperinflation associated with poorer lung function but better bronchodilator responsiveness

Abstract

Background

It is unknown whether aggressive medication strategies should be used for early COPD with or without lung hyperinflation. We aimed to explore the characteristics and bronchodilator responsiveness of early COPD patients (stages I and II) with/without lung hyperinflation.

Methods

Four hundred and six patients with COPD who performed both lung volume and bronchodilation tests were retrospectively analyzed. Residual volume to total lung capacity >120% of predicted values indicated lung hyperinflation. The characteristics and bronchodilator responsiveness were compared between the patients with and without lung hyperinflation across all stages of COPD.

Results

The percentages of patients with lung hyperinflation were 72.7% in the entire cohort, 19.4% in stage I, 68.5% in stage II, 95.3% in stage III, and 100.0% in stage IV. The patients with lung hyperinflation exhibited poorer lung function but better bronchodilator responsiveness of both forced expiratory volume in 1 second and forced vital capacity than those without lung hyperinflation during early COPD (t=2.21–5.70, P=0.000–0.029), especially in stage I, while age, body mass index, smoking status, smoking history, and disease duration were similar between the two subgroups in the same stages. From stages I to IV of subgroups with lung hyperinflation, stage I patients had the best bronchodilator responsiveness. Use of bronchodilator responsiveness of forced vital capacity to detect the presence of lung hyperinflation in COPD patients showed relatively high sensitivities (69.5%–75.3%) and specificities (70.3%–75.7%).

Conclusion

We demonstrated the novel finding that early COPD patients with lung hyperinflation are associated with poorer lung function but better bronchodilator responsiveness and established a simple method for detecting lung hyperinflation.

Keywords:

• GOLD I
• GOLD II
• RV/TLC
• bronchodilation test

Acknowledgments

This work was supported by chronic respiratory diseases funding, Chinese Medical Association research projects, National Key Technology R&D Program, and Natural Science Foundation for Young of China (2012BAI05B01, 2013BAI09B09, 2014Y2-00540, 2015BAI12B10, 81300017).

Author contributions

JZ is the guarantor of the paper, had full access to all the data in the study, and takes responsibility for the integrity of the data and the accuracy of the data analysis. WJ contributed to study design, quality control, acquisition of the data, statistical analysis, and revising of the manuscript. CC contributed to quality control, acquisition of the data, statistical analysis, and drafting of the manuscript. All authors contributed toward data analysis, drafting and revising the paper and agree to be accountable for all aspects of the work. All the authors have read and approved the final manuscript.

Disclosure

The authors report no conflicts of interest in this work.