Disease progression in young patients with COPD: rethinking the Fletcher and Peto model

Chronic obstructive pulmonary disease (COPD), although frequent in older individuals, can also occur at younger age; this latter population has not been well described. We reviewed the functional progression of 1708 patients with COPD attending pulmonary clinics. Those with three or more annual spirometries were divided into those who, at enrolment, were ≤ 55 (n = 103) or ≥ 65 (n = 463) years of age (younger and older COPD, respectively). Baseline and annual changes in lung function (forced expiratory volume in 1 s (FEV1)) and BODE (body mass index, airflow obstruction, dyspnoea, exercise capacity) score were recorded and compared between both groups. Severity distribution by Global Initiative for Chronic Obstructive Lung Disease and BODE scores were similar in both groups, except for mild obstruction, which was higher in the younger group. Mean FEV1 decline was 38.8 and 40.6 mL · year(-1), while BODE scores increased 0.19 and 0.23 units per year, for younger and older COPD, respectively. Both groups had similar proportion of FEV1 rapid decliners (42% and 46%, respectively). The severity distribution and progression of disease in younger patients with COPD is similar to that of patients of older age. This observation suggests that younger individuals presenting with COPD develop the disease from an already compromised pulmonary and systemic status, complementing the model of steeper decline of lung function proposed by Fletcher and Peto.