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Firdaus A. A. Mohamed Hoesein, MD, PhD; Pieter Zanen, MD, PhD
Author and Funding Information

From the Division of Heart and Lungs, Department of Respiratory Medicine, University Medical Center Utrecht.

Correspondence to: Pieter Zanen, MD, PhD, University Medical Center Utrecht, Heidelberglaan 100, Utrecht, The Netherlands; e-mail: p.zanen@umcutrecht.nl


Financial/nonfinancial disclosures: The authors have reported to CHEST that no potential conflicts of interest exist with any companies/organizations whose products or services may be discussed in this article.

Reproduction of this article is prohibited without written permission from the American College of Chest Physicians. See online for more details.


Chest. 2012;142(6):1694-1695. doi:10.1378/chest.12-1813
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To the Editor:

We thank Drs Aggarwal and colleagues for their valuable questions about and remarks on our article in CHEST.1 To start with, we would like to emphasize that the included subjects were heavy smokers drawn from the general population: Non-smoking-related diseases would show a study prevalence equal to that in the population. Asthma would, therefore, be present in the same (low) population percentage in all the groups we formed. As mentioned in the “Materials and Methods” section, the three groups were based on the baseline prebronchodilator FEV1/FVC: either >70%, ≤70% and greater than the lower limit of normal, or less than or equal to the lower limit of normal. Because asthma was neither an inclusion nor an exclusion criterion, asthmatic subjects were fully randomized over the three groups formed. The effect on lung function decline was therefore negligible.

The aim of the current study was to relate baseline FEV1/FVC to lung function decline in heavy smokers. We agree that COPD is also known to occur in nonsmokers; nonetheless, the majority of COPD in the Western World is caused by tobacco smoke and only a small minority by other causes. The subjects in this study originated from the concise Utrecht and Groningen areas in The Netherlands, and the air pollution burdens for the included subjects are very comparable. No large contrasts in terms of heavily polluted urban areas as opposed to nonindustrialized farming areas exist.

The subjects in this observational study were not subjected to treatment as a result of the study findings. In addition, there is now evidence that neither bronchodilator nor steroid treatment significantly influences the decline of lung function over time.2,3 Our study included mostly heavy smokers with an FEV1/FVC >70% and with mild COPD. It has been shown that the number of exacerbations is low in GOLD (Global Initiative for Chronic Obstructive Lung Disease) stage II, and so it is not surprising that in our cohort the probability of prior exacerbations is even lower.4 An exacerbation effect on FEV1 decline is, therefore, minute and undetectable.

References

Mohamed Hoesein FAA, Zanen P, Boezen HM, et al. Lung function decline in male heavy smokers relates to baseline airflow obstruction severity. Chest. 2012;142(6):1530-1538.
 
Tashkin DP, Celli B, Senn S, et al; UPLIFT Study Investigators. A 4-year trial of tiotropium in chronic obstructive pulmonary disease. N Engl J Med. 2008;359(15):1543-1554. [CrossRef] [PubMed]
 
Celli BR, Thomas NE, Anderson JA, et al. Effect of pharmacotherapy on rate of decline of lung function in chronic obstructive pulmonary disease: results from the TORCH study. Am J Respir Crit Care Med. 2008;178(4):332-338. [CrossRef] [PubMed]
 
Hurst JR, Vestbo J, Anzueto A, et al; ECLIPSE Investigators. Susceptibility to exacerbation in chronic obstructive pulmonary disease. N Engl J Med. 2010;363(12):1128-1138. [CrossRef] [PubMed]
 

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References

Mohamed Hoesein FAA, Zanen P, Boezen HM, et al. Lung function decline in male heavy smokers relates to baseline airflow obstruction severity. Chest. 2012;142(6):1530-1538.
 
Tashkin DP, Celli B, Senn S, et al; UPLIFT Study Investigators. A 4-year trial of tiotropium in chronic obstructive pulmonary disease. N Engl J Med. 2008;359(15):1543-1554. [CrossRef] [PubMed]
 
Celli BR, Thomas NE, Anderson JA, et al. Effect of pharmacotherapy on rate of decline of lung function in chronic obstructive pulmonary disease: results from the TORCH study. Am J Respir Crit Care Med. 2008;178(4):332-338. [CrossRef] [PubMed]
 
Hurst JR, Vestbo J, Anzueto A, et al; ECLIPSE Investigators. Susceptibility to exacerbation in chronic obstructive pulmonary disease. N Engl J Med. 2010;363(12):1128-1138. [CrossRef] [PubMed]
 
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