Incidence of airflow limitation in subjects 65–100 years of age

The true incidence of chronic obstructive pulmonary disease is largely unknown, because the few longitudinal studies performed have used diagnostic criteria no longer recommended by either the European Respiratory Society or the American Thoracic Society (ATS). We studied the incidence and significance of airflow limitation in a population-based geriatric sample using both an age-dependent predicted lower limit of normal (LLN) value and a fixed-ratio spirometric criterion. Out of 2025 subjects with acceptable spirometry at baseline, 984 subjects aged 65–100 years completed a 6-year follow-up visit. Smoking habits were registered at baseline. Exclusion criteria were non-acceptable spirometry performance according to ATS criteria and inability to communicate. Airflow limitation was defined both according to forced expiratory volume in 1 s (FEV(1))/forced vital capacity ratio <0.7 and <LLN. The incidence of airflow limitation per 1000 person-years was 28.2 using a fixed ratio and 11.7 with LLN, corresponding to a 1.41-fold higher incidence rate using a fixed ratio. The incidence increased dramatically with age when using a fixed ratio, but less so when using LLN. In addition, a sex effect was observed with the LLN criterion. LLN airflow limitation was associated with increased 5-year mortality. Presence of fixed-ratio airflow limitation in individuals classified by LLN as non-obstructive was not associated with increased mortality.