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 by managing symptoms pharmaceutically.
COPD is diagnosed using a spirometry test, where a patient exhales as hard as possible. Two measurements are taken: the forced vital capacity (FVC), which is the total volume of air exhaled, and the forced expiratory volume (FEV1), which is the volume exhaled in the first second. In sufferers of COPD, FVC is normal but FEV1 is reduced due to the damage to the airways. Spirometry can also be used to differentiate between COPD and the similar condition asthma: for an asthma sufferer without COPD, bronchodilator medicines would open up the airways to produces a normal FEV1 measurement 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 6th 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, an observational study by Josephs et al. (2019) suggested that COPD in the UK is mis- or over-diagnosed in certain groups based on absence or irregularity of spirometry measurements. Misdiagnosis was thought to particularly affect women, never-smokers and those with higher 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.
