Health outcomes associated with excessive lung function decline and respiratory symptoms in a community cohort

Background: In creating workplace respiratory disease prevention strategies, a thorough understanding is needed of the relative contributions of lung function loss and respiratory symptoms and disease to predict health outcomes. Methods: Copenhagen City Heart Study data collected at four examinations during 1976–2003 were used to assess risk associated with excessive lung function decline and respiratory symptoms and disease. Risks of chronic obstructive pulmonary disease (COPD) morbidity, COPD or coronary heart disease (CHD) mortality, and all-cause mortality were estimated in relation to asthma, chronic bronchitis, shortness of breath, and cross-sectional lung function or with one of four criteria for longitudinal lung function decline over five years of follow-up. Hazard ratios (HR) and 95% confidence intervals (CI) estimated the relationships between lung function parameters and event rates by gender and for never smokers. Age, height-adjusted baseline lung function (FEV₁/Height²), and height were adjusted for in the models. Results: For COPD morbidity, the increasing trend in the HR (95% CI) by quartiles of the slope was 1.61 (1.18–2.19), 2.54 (1.87–3.45), and 3.77 (2.76–5.15) for males; 2.48 (1.89–3.27), 3.37 (2.55–4.44), and 6.12 (4.63–8.10) for females; and 1.89 (0.76–4.69), 2.25 (0.88–5.78), and 4.14 (1.57–10.90) for never smokers. The risk of COPD or CHD mortality and of all-cause mortality also showed a significant increasing trend. Discussion: The risk of respiratory morbidity and mortality showed an increasing trend with lung function decline after adjustment for baseline lung function and respiratory symptoms and disease.