The natural history of COPD: confirming and going beyond Fletcher and Peto.

In this issue of the European Respiratory Journal (ERJ), SANCHEZ-SALCEDO et al. [3] contribute to our knowledge of chronic obstructive pulmonary disease (COPD) clinical status and progression in a study of 103 younger and 463 older patients followed for o2 years. All patients attended specialised pulmonary clinics, had smoked for o20 pack-years and were (presumably) symptomatic from their physiciandiagnosed COPD. The majority (59%) of the younger patients were ‘‘active smokers’’ compared with only 20% of the older group. The rapid decliners in this study may be considered similar to the susceptible smokers who demonstrated rapid decline in the study by FLETCHER and PETO [1]. The Fletcher–Peto cohort was a random sample of 792 employed middle-aged Caucasian males who were followed for 8 years. Presciently, 37 years ago, this cohort demonstrated that not all smokers are susceptible to losing lung function and that in the susceptible smokers, continued smoking accelerates loss. As in the Fletcher–Peto cohort, which followed only males, and in the BODE (body mass index, airflow obstruction, dyspnoea, exercise capacity) cohort study by CASANOVA et al. [4], in which 92% were male, the study by SANCHEZSALCEDO et al. [3] is heavily weighted to males, with 85% of the younger and 92% of the older patients being male. Data on females were provided by the Framingham Offspring Cohort [5] (4391 community residents followed for 23 years, of whom 51% were females) and by the Lung Health Study [6] (5885 COPD patients followed for o14.5 years, of whom 37% were females). The absence of data on females renders the study by SANCHEZ-SALCEDO et al. [3] less applicable to population analysis for rates of change in forced expiratory volume in 1 s (FEV1). The Framingham cohort showed a lower decline in females who continued to smoke compared with males (23.9 versus 38.2 mL?yr), and fewer female smokers who developed airflow obstruction (24.2%) than male smokers (33.0%) [5].