Does Spirometry Still Measure Up in the Diagnosis of COPD?

Abstract

An adequate and early diagnosis of COPD is essential for an appropriate and efficient treatment of this debilitating disease. Currently, spirometry is required to establish a diagnosis of COPD in patients with chronic respiratory symptoms or in those at risk.1Global Initiative for Chronic Obstructive Lung Disease Global strategy for diagnosis, management, and prevention of COPD. Global Initiative for Chronic Obstructive Lung Disease website.http://www.goldcopd.org/Google Scholar According to the results reported in CHEST (December 2012) by Mohamed Hoesein et al,2Mohamed Hoesein FAA Zanen P Boezen HM et al.Lung function decline in male heavy smokers relates to baseline airflow obstruction severity.Chest. 2012; 142: 1530-1538Abstract Full Text Full Text PDF PubMed Scopus (21) Google Scholar this approach would misdiagnose an important group of patients who do not (yet) fulfill the spirometry diagnostic criteria; that is, among male heavy smokers, those with higher FEV1/FVC ratios may be the ones with the fastest FEV1 decline, a hallmark of COPD. However, from their regression model that exposed potential confounders, it appears that a higher level of FEV1 actually preserved airflow.2Mohamed Hoesein FAA Zanen P Boezen HM et al.Lung function decline in male heavy smokers relates to baseline airflow obstruction severity.Chest. 2012; 142: 1530-1538Abstract Full Text Full Text PDF PubMed Scopus (21) Google Scholar Adjustments for this confounder would have subsequently disfavored individuals with higher FEV1/FVC ratios. I wonder how the different groups would compare without these adjustments. Moreover, a recent article by Akkermans et al3Akkermans RP Berrevoets MA Smeele IJ et al.Lung function decline in relation to diagnostic criteria for airflow obstruction in respiratory symptomatic subjects.BMC Pulm Med. 2012; 12: 12Crossref PubMed Scopus (26) Google Scholar revealed a faster FEV1 decline for patients with lower FEV1/FVC ratios in both smokers and nonsmokers. Although the ECLIPSE (Evaluation of COPD Longitudinally to Identify Predictive Surrogate Endpoints), UPLIFT (Understanding Potential Long-term Impacts on Function With Tiotropium), and TORCH (Towards a Revolution in COPD Health) trials indeed found FEV1 decline to be inversely related to GOLD (Global Initiative for Chronic Obstructive Lung Disease) stage, as recognized by Mohamed Hoesein et al,2Mohamed Hoesein FAA Zanen P Boezen HM et al.Lung function decline in male heavy smokers relates to baseline airflow obstruction severity.Chest. 2012; 142: 1530-1538Abstract Full Text Full Text PDF PubMed Scopus (21) Google Scholar this effect may as well be explained by the inverse relation across all studies between GOLD stage and the prevalence of current smoking, the most important factor for FEV1 decline.4Agusti A Calverley PM Celli B Evaluation of COPD Longitudinally to Identify Predictive Surrogate Endpoints (ECLIPSE) Investigators et al.Characterisation of COPD heterogeneity in the ECLIPSE cohort.Respir Res. 2010; 11: 122Crossref PubMed Scopus (874) Google Scholar, 5Kesten S Celli B Decramer M Liu D Tashkin D Adverse health consequences in COPD patients with rapid decline in FEV1—evidence from the UPLIFT trial.Respir Res. 2011; 12: 129Crossref PubMed Scopus (25) Google Scholar, 6Jenkins CR Jones PW Calverley PM et al.Efficacy of salmeterol/fluticasone propionate by GOLD stage of chronic obstructive pulmonary disease: analysis from the randomised, placebo-controlled TORCH study.Respir Res. 2009; 10: 59Crossref PubMed Scopus (304) Google Scholar, 7Vestbo J Edwards LD Scanlon PD ECLIPSE Investigators et al.Changes in forced expiratory volume in 1 second over time in COPD.N Engl J Med. 2011; 365: 1184-1192Crossref PubMed Scopus (734) Google Scholar Whether a horse-racing effect should be acknowledged in the progression of COPD remains undecided. As yet, the current spirometry diagnostic criteria appear to remain crucial in the diagnosis of COPD. In the end, one of the striking results from this cohort appears to be the relatively high FEV1 decline in heavy smokers. Apart from an adequate diagnosis of COPD, smoking may still be the most important and practical tool to predict future disease and may as well be the most important feature at which to direct intervention. ResponseCHESTVol. 143Issue 1PreviewWe appreciate the correspondence of Dr van Dijk on our study in CHEST,1 in which we examined lung function decline in three groups of heavy smokers classified by their baseline prebronchodilator FEV1/FVC: >70%, ≤70%, and less than the lower limit of normal. We believe that Dr van Dijk misinterpreted the outcomes reported in Table 4. As can be found in the “Materials and Methods” section,1 the decline was analyzed by multiple linear regression with the follow-up FEV1 as the dependent variable and the baseline FEV1, among others, as an independent variable. Full-Text PDF