Chronic obstructive pulmonary disease with mild airflow limitation: current knowledge and proposal for future research – a consensus document from six scientific societies

Abstract

Chronic obstructive pulmonary disease (COPD) is a leading cause of mortality and morbidity worldwide, with high and growing prevalence. Its underdiagnosis and hence under-treatment is a general feature across all countries. This is particularly true for the mild or early stages of the disease, when symptoms do not yet interfere with daily living activities and both patients and doctors are likely to underestimate the presence of the disease. A diagnosis of COPD requires spirometry in subjects with a history of exposure to known risk factors and symptoms. Postbronchodilator forced expiratory volume in 1 second (FEV1)/forced vital capacity <0.7 or less than the lower limit of normal confirms the presence of airflow limitation, the severity of which can be measured by FEV1% predicted: stage 1 defines COPD with mild airflow limitation, which means postbronchodilator FEV1 ≥80% predicted. In recent years, an elegant series of studies has shown that “exclusive reliance on spirometry, in patients with mild airflow limitation, may result in underestimation of clinically important physiologic impairment”. In fact, exercise tolerance, diffusing capacity, and gas exchange can be impaired in subjects at a mild stage of airflow limitation. Furthermore, growing evidence indicates that smokers without overt abnormal spirometry have respiratory symptoms and undergo therapy. This is an essential issue in COPD. In fact, on one hand, airflow limitation, even mild, can unduly limit the patient’s physical activity, with deleterious consequences on quality of life and even survival; on the other hand, particularly in younger subjects, mild airflow limitation might coincide with the early stage of the disease. Therefore, we thought that it was worthwhile to analyze further and discuss this stage of “mild COPD”. To this end, representatives of scientific societies from five European countries have met and developed this document to stimulate the attention of the scientific community on COPD with “mild” airflow limitation. The aim of this document is to highlight some key features of this important concept and help the practicing physician to understand better what is behind “mild” COPD. Future research should address two major issues: first, whether mild airflow limitation represents an early stage of COPD and what the mechanisms underlying the evolution to more severe stages of the disease are; and second, not far removed from the first, whether regular treatment should be considered for COPD patients with mild airflow limitation, either to prevent progression of the disease or to encourage and improve physical activity or both.

Effects of meteorological conditions on mortality from chronic obstructive pulmonary disease

“…The death rate from COPD grew by 15% during the five-year period. A particularly high increase of COPD prevalence and death rate observed in women were also reported by some other authors [1,15].…”

Forced oscillation technique for early detection of the effects of smoking and COPD: contribution of fractional-order modeling

“… 14 FOT was successfully applied in our laboratory and in several other research groups to diagnose early respiratory changes in respiratory mechanics. 13 , 15 – 26 …”

Female reproductive history in relation to chronic obstructive pulmonary disease and lung function in UK biobank: a prospective population-based cohort study

“…This inconsistency may be explained by the fact that spirometry was measured in participants at baseline (age 40 to 69) and FEV 1 and FEV 1 /FVC may have declined during follow-up. Conversely, many patients diagnosed with stage 1 COPD do not go on to develop COPD symptoms or COPD resulting in hospitalisation/death 27. There is also high intra-individual variability in FEV 1 28.…”