Prevalence, Characteristics, and Prognosis of Early Chronic Obstructive Pulmonary Disease. The Copenhagen General Population Study

Abstract

Rationale: Identification of younger adults at high risk of developing chronic obstructive pulmonary disease (COPD) could lead to implementation of preventive measures before disease onset and halt progression.Objectives: To investigate the prevalence, characteristics, and prognosis of individuals with early COPD in the general population.Methods: We investigated 105,630 randomly chosen adults from a Danish contemporary population-based cohort. Early COPD was defined as FEV₁/FVC less than the lower limit of normal in individuals under 50 years of age with 10 pack-years or greater of tobacco consumption.Measurements and Main Results: Among 8,064 individuals under 50 years of age with 10 pack-years or greater of tobacco consumption, 1,175 (15%) had early COPD, of whom 58% were current smokers. Individuals with early COPD more often had chronic respiratory symptoms, severe lung function impairment, asthma, and a history with bronchitis/pneumonia. During the 14.4-year follow-up, we observed 117 acute hospitalizations with obstructive lung disease, 227 acute hospitalizations with pneumonia, and 185 deaths among the 8,064 younger adults. Compared with individuals without COPD, those with early COPD had multivariable adjusted hazard ratios of 6.42 (95% confidence interval, 3.39-12.2) for acute obstructive lung disease hospitalizations, 2.03 (1.43-2.88) for acute pneumonia hospitalizations, and 1.79 (1.28-2.52) for all-cause mortality.Conclusions: Among individuals under 50 years of age and 10 pack-years or greater of tobacco consumption from the general population, 15% fulfill criteria of early COPD. Individuals with early COPD more often have chronic respiratory symptoms and severe lung function impairment, and an increased risk of acute respiratory hospitalizations and early death.

Keywords: FEV; airway obstruction; chronic bronchitis; diagnosis; emphysema.

Figure 1.

Study population. Symptoms included chronic mucus hypersecretion, dyspnea, wheezing, and/or cough. COPD = chronic obstructive pulmonary disease; LLN = lower limit of normal.

Figure 2.

Prevalence of FEV₁/FVC less than the lower limit of normal (LLN) according to age and amount of tobacco consumption. Included individuals are smokers under 50 years of age. Symptoms included chronic mucus hypersecretion, dyspnea, wheezing, and/or cough.

Figure 3.

Cumulative incidence of acute hospitalizations due to obstructive lung disease and pneumonia and of death in individuals with and without early chronic obstructive pulmonary disease (COPD). Included individuals are under 50 years of age with 10 pack-years or greater of tobacco consumption. Early COPD was defined as FEV₁/FVC less than the lower limit of normal.

Figure 4.

Risk of acute hospitalizations due to obstructive lung disease and pneumonia and of death in individuals with and without early chronic obstructive pulmonary disease (COPD). Included individuals are under 50 years of age with 10 pack-years or greater of tobacco consumption. Early COPD was defined as FEV₁/FVC less than the lower limit of normal. Analyses were adjusted for age (as timescale), sex, smoking status, and pack-years of tobacco consumption. CI = confidence interval; HR = hazard ratio.

Figure 5.

Risk of acute hospitalizations due to obstructive lung disease and pneumonia and of death in symptomatic and asymptomatic individuals with and without early chronic obstructive pulmonary disease (COPD). Included individuals are under 50 years of age with 10 pack-years or greater of tobacco consumption. Early COPD was defined as FEV₁/FVC less than the lower limit of normal. Symptoms included chronic mucus hypersecretion, dyspnea, wheezing, and/or cough. Analyses were adjusted for age (as timescale), sex, smoking status, and pack-years of tobacco consumption. CI = confidence interval; HR = hazard ratio.

Figure 6.

Risk of acute hospitalizations due to obstructive lung disease and pneumonia and of death in individuals with early chronic obstructive pulmonary disease (COPD). Early COPD was defined as FEV₁/FVC less than the lower limit of normal in individuals under 50 years of age with 10 pack-years or greater of tobacco consumption. Analyses were adjusted for age (as timescale), sex, smoking status, and pack-years of tobacco consumption. Symptoms included chronic mucus hypersecretion, dyspnea, wheezing, and/or cough. P value for interaction with covariates was calculated in individuals under 50 years of age with 10 pack-years or greater of tobacco consumption with and without early COPD on risk of acute hospitalizations and death. CI = confidence interval; HR = hazard ratio; mMRC = modified Medical Research Council dyspnea scale.