Smoking is a major environmental risk factor for chronic obstructive pulmonary disease (COPD). However, COPD is also prevalent among nonsmokers, especially in low- and middle-income countries (LMICs), where they account for up to 60-70% of cases. Indoor air pollution due to biomass burning is the major non-smoking risk factor in such cases. Other risk factors include occupational exposures to dusts, fumes, outdoor air pollutants such as particulate matter, nitrogen oxides (NOx), sulfur oxides (SOx), socioeconomic status, asthma and airway hyperreactivity and abnormal lung development. The most common genetic risk factor for COPD is a-1 antitrypsin deficiency.

An interplay of environmental and genetic risk factors predisposes to the development of COPD among susceptible individuals.

The earlier GOLD guidelines took into consideration these risk factors and incorporated them in the definition of COPD as “a common, preventable and treatable disease that is characterized by persistent respiratory symptoms and airflow limitation that is due to airway and/or alveolar abnormalities usually caused by significant exposure to noxious particles or gases and influenced by host factors including abnormal lung development.”

However, the latest 2023 GOLD guidelines¹ opine that “the definition of a disease should only include the characteristics that distinguishes it from other diseases”. Hence, they have proffered a new definition of COPD as “a heterogeneous lung condition characterized by chronic respiratory symptoms (dyspnea, cough, expectoration, exacerbations) due to abnormalities of the airways (bronchitis, bronchiolitis) and/or alveoli (emphysema) that cause persistent, often progressive, airflow obstruction.” Etiologic and risk factors have not been included in this updated definition, which highlights “patient characteristics”.

Few new terminologies have been introduced in the new GOLD guidelines.

• Early COPD: This term indicates the “biological early” disease in an experimental setting and relates to the disease mechanisms and not “clinical early” disease when symptoms first begin to manifest.

• Mild COPD:Mild disease can occur at any age, not necessarily in a younger age. Discounting mild disease as a synonym for early disease, GOLD 2023 has proposed that the term “mild” should be used only to denote the severity of airflow obstruction as measured on spirometry.

• Young COPD: The guidelines state that peak lung function occurs around 20 years of age and begins to wane at 40-50 years age. Hence, the term young COPD denotes patients in the age group 20-50 years.

• Pre-COPD: This indicates people with respiratory symptoms, which may or may not be accompanied by structural (such as emphysema) and/or abnormalities in lung function (such as rapid fall in FEV1, reduced lung diffusing capacity) but with no evidence of airflow obstruction on post-bronchodilator spirometry (FEV1/FVC>0.7). Regardless, they should be considered as patients.

• PRISm:Preserved Ratio Impaired Spirometry (PRISm) has been included to denote persons, particularly current and former smokers, who have no evidence of airflow obstruction (FEV1/FVC ≥ 0.7) but have abnormal spirometry (FEV1 < 80% of reference after bronchodilation). It can progress to obstructive or restrictive disease or may transition to normal. This term had initially been categorised as “unclassified” (GOLD-U).

Reference

1. Agusti A, et al. Global Initiative for Chronic Obstructive Lung Disease 2023 Report: GOLD Executive Summary. Am J Respir Crit Care Med. 2023 Mar 1. doi: 10.1164/rccm.202301-0106PP.