Abstract

Relevant information on the prevalence of chronic obstructive pulmonary disease (COPD) and its trends is scarce. In the present study, we compare the prevalence rates and potential determinants of COPD in two national population samples that were surveyed 20 yrs apart. In 1978-1980, a sample of 8,000 people was surveyed; subjects were representative of the Finnish population and were aged ≥30 yrs. Among those aged 30-74 yrs, acceptable spirometry was obtained from 6,364 (87%) subjects. In a similar survey conducted in 2000-2001, comparable spirometry was obtained from 5,495 (80%) participants. Airway obstruction was defined as forced expiratory volume in 1 s (FEV(1))/forced vital capacity below the lower limit of normal and staged for severity on the basis of FEV(1) % predicted. The age-adjusted prevalence rates of obstruction (stages I-IV) were rather similar in both surveys in males (4.7 versus 4.3%; p = 0.25), but were almost significantly higher in females in the later survey (2.2 versus 3.1%; p = 0.06). The rates of COPD stage II or higher were 3.9% in 1978-1980, and 3.6% in 2000-2001 (p = 0.36) for males, and 1.4 and 1.5% (p = 0.93), respectively, for females. In conclusion, no significant difference was found in the prevalence of COPD stages II-IV between similar population based surveys performed 20 yrs apart. Since COPD is mostly mild or moderate there is a strong case for early prevention.