Chronic obstructive pulmonary disease (COPD): introduction

Chronic Obstructive Pulmonary Disease (COPD) refers to a group of lung conditions which restrict airflow to the lungs and cause breathing problems, including emphysema and chronic bronchitis. Emphysema occurs when the alveoli in the lungs are damaged, making oxygen uptake into the bloodstream less efficient and exhaling more challenging. Chronic bronchitis describes the long-term inflammation of the bronchi which constricts the airways and impedes airflow to the lungs. Both conditions are caused primarily by smoking.

In addition to respiratory symptoms such as shortness of breath, persistent mucus-producing cough, frequent chest infections, and wheezing, sufferers can also experience fatigue and weight loss. Additionally, COPD is associated with, and may contribute towards, numerous co-existing diseases such as heart disease, osteoporosis and diabetes. COPD is a progressive and incurable disease; therefore, treatment focuses on slowing progression by quitting smoking and improving exercise tolerance, as well as managing symptoms pharmaceutically.

COPD is diagnosed and distinguished from similar conditions like asthma using a spirometry test, where a patient exhales as hard as possible into a spirometer. Measurements are taken of the total volume of air exhaled as well as the rate of flow of air in the first second. In COPD sufferers, the flow of air is impaired, but the total volume exhaled is normal. In asthma sufferers without COPD, bronchodilator medicines open up the airways to produce normal flow measurements whereas in COPD airflow obstruction cannot be fully reversed by medicine. In addition to diagnosis, spirometry can be used to monitor progression of COPD and the impact of treatment.

COPD is a major contributor to morbidity and mortality in Scotland and worldwide, with the 2021 Global Burden of Disease study finding COPD to be the sixth largest contributor to combined morbidity and mortality in Scotland. These estimates likely underestimate the burden of COPD, as the National Institute for Health and Care Excellence (NICE) estimates that approximately two thirds of COPD cases in the UK are undiagnosed. Conversely, there is some evidence to suggest that COPD is mis- or over-diagnosed in the UK in certain groups based on absence of or irregularity of spirometry measurements (Josephs et al, 2019; Perret et al, 2023). Misdiagnosis was thought to particularly affect women, never-smokers and those with higher body mass index (BMI).

Acknowledgments: ScotPHO would like to thank Dr Philip Conaglen, who prepared the original version of these pages on COPD. We also acknowledge the very helpful comments of the University of Edinburgh's Allergy and Respiratory Research Group.