GOLD COPD stage I is not associated with increased risk of death

Abstract

Hoesein et al.,1Hoesein F.A.A.M. Zanen P. Lammers J.-W.J. Lower limit of normal or FEV1/FVC < 0.70 in diagnosing COPD: an evidence-based review.Respiratory Medicine. 2011; 105: 907-915Abstract Full Text Full Text PDF PubMed Scopus (130) Google Scholar in a comprehensive and balanced review of the literature, addressed the question whether the diagnosis of airways obstruction should be based on an FEV1/FVC ratio < 0.70 (fixed ratio), or below the lower limit of normal (LLN, commonly the 5th centile). A clinical diagnosis is commonly confirmed by combining clinical information with test results, presented with their lower and upper limits of normal. The GOLD committee deviated from the time-honoured and scientifically based practise by replacing the LLN with a fixed FEV1/FVC ratio,2Global strategy for diagnosis, management, and prevention of COPD. Updated 2010. www.goldcopd.com, [accessed 18.03.11].Google Scholar with no evidence that this was a valid way of diagnosing airways obstruction, aka chronic obstructive lung disease (COPD). Many studies have since unsuccessfully tried to find evidence that there may be any merit in using the fixed ratio for diagnosing COPD. Hoesein et al.’s1Hoesein F.A.A.M. Zanen P. Lammers J.-W.J. Lower limit of normal or FEV1/FVC < 0.70 in diagnosing COPD: an evidence-based review.Respiratory Medicine. 2011; 105: 907-915Abstract Full Text Full Text PDF PubMed Scopus (130) Google Scholar final conclusion hinges on one publication3Mannino D.M. Buist A.S. Vollmer W.M. Chronic obstructive pulmonary disease in the older adult: what defines abnormal lung function?.Thorax. 2007; 62: 237-241Crossref PubMed Scopus (122) Google Scholar; it allegedly showed that subjects with an FEV1/FVC ratio < 0.70 but > LLN had an increased risk of premature death and hospitalisation for COPD. However, the adjusted hazard ratio for death was misquoted: it was not elevated (1.1, confidence interval 0.96–1.3, see table 3 in3Mannino D.M. Buist A.S. Vollmer W.M. Chronic obstructive pulmonary disease in the older adult: what defines abnormal lung function?.Thorax. 2007; 62: 237-241Crossref PubMed Scopus (122) Google Scholar). An increased hazards ratio for hospitalisation was reported, but the authors conceded that ‘the measure of COPD-related hospitalisations was too inclusive’,4Mannino D.M. Buist A.S. Vollmer W.M. Authors’ reply to two letters to the editor.Thorax. 2007; 62: 1108-1109Crossref Scopus (213) Google Scholar so this finding also fails under scrutiny. Regardless, it is circular reasoning to postulate that an FEV1/FVC ratio < 0.70 represents COPD, and subsequently consider any death or hospitalisation in subjects with such a ratio as confirming the diagnosis of COPD. Subjects with FEV1/FVC < LLN, but not non-smokers with FEV1/FVC < 0.70 but > LLN, have an increased risk of all-cause death.5Vaz Fragoso C.A. Concato J. McAvay G. et al.The ratio of forced expiratory volume in 1-second to forced vital capacity as a basis for establishing chronic obstructive pulmonary disease.American Journal of Respiratory and Critical Care Medicine. 2010; 181: 446-451Crossref PubMed Scopus (109) Google Scholar, 6Vaz Fragoso C. Gill T. McAvay G. et al.Evaluating respiratory impairment in middle-agedpersons using lambda-mu-sigmaderived z-scores.Respiratory Care. 2011 May 20; ([Epub ahead of print])PubMed Google Scholar GOLD stage I in asymptomatic subjects is not associated with dyspnoea, accelerated decline in FEV1, respiratory care utilisation or quality of life scores compared with a reference group.7Bridevaux P.O. Gerbase M.W. Probst-Hensch N.M. et al.Long-term decline in lung function, utilisation of care and quality of life in modified GOLD stage 1 COPD.Thorax. 2008; 63: 768-774Crossref PubMed Scopus (117) Google Scholar It is therefore safe to assume that GOLD COPD stage I in the above studies3Mannino D.M. Buist A.S. Vollmer W.M. Chronic obstructive pulmonary disease in the older adult: what defines abnormal lung function?.Thorax. 2007; 62: 237-241Crossref PubMed Scopus (122) Google Scholar, 5Vaz Fragoso C.A. Concato J. McAvay G. et al.The ratio of forced expiratory volume in 1-second to forced vital capacity as a basis for establishing chronic obstructive pulmonary disease.American Journal of Respiratory and Critical Care Medicine. 2010; 181: 446-451Crossref PubMed Scopus (109) Google Scholar, 6Vaz Fragoso C. Gill T. McAvay G. et al.Evaluating respiratory impairment in middle-agedpersons using lambda-mu-sigmaderived z-scores.Respiratory Care. 2011 May 20; ([Epub ahead of print])PubMed Google Scholar represented healthy subjects with FEV1/FVC > LLN. All the evidence, including that from all longitudinal studies, is therefore that GOLD COPD stage I does not represent disease. Therefore the ‘twilight zone’ (FEV1/FVC < 0.70 but > LLN) deserves no attention. Apart from smoking cessation, for which all smokers should get all the help available regardless of pulmonary function, there is no intervention that will favourably affect their lung condition. As the authors and Bridevaux et al.7Bridevaux P.O. Gerbase M.W. Probst-Hensch N.M. et al.Long-term decline in lung function, utilisation of care and quality of life in modified GOLD stage 1 COPD.Thorax. 2008; 63: 768-774Crossref PubMed Scopus (117) Google Scholar suggest, in establishing a diagnosis one should put more emphasis on prior probability of disease, clinical signs and symptoms. Dr. Furberg and myself have no conflict of interest to declare.