Background: COPD is a major cause of chronic morbidity and mortality throughout the world. Although the prevalence of COPD is already well documented, there are only few studies regarding the incidence of COPD.
Methods: In a prospective population-based cohort study among subjects aged >or= 55 years, COPD was diagnosed with an algorithm based on the validation of hospital discharge letters, files from the general practitioner, and spirometry reports.
Results: In this study cohort of 7,983 participants, 648 cases were identified with incident COPD after a median follow-up time of 11 years (interquartile range, 7.8 years). This resulted in an overall incidence rate (IR) of 9.2/1,000 person-years (PY) [95% confidence interval (CI), 8.5 to 10.0]. The IR of COPD was higher among men (14.4/1,000 PY; 95% CI, 13.0 to 16.0) than among women (6.2/1,000 PY; 95% CI, 5.5 to 7.0), and higher in smokers than in never-smokers (12.8/1,000 PY; 95% CI, 11.7 to 13.9 and 3.9/1,000 PY; 95% CI, 3.2 to 4.7, respectively). Remarkable was the high incidence in the youngest female age category of 55 to 59 years (7.4/1,000 PY; 95% CI, 4.1 to 12.6). For a 55-year-old man and woman still free of COPD at cohort entry, the risk for the development of COPD over the coming 40 years was 24% and 16%, respectively.
Conclusion: The overall incidence of COPD in an elderly population is 9.2/1,000 PY, with a remarkably high incidence in the youngest women, suggesting a further shift toward the female sex in the gender distribution of COPD. During their further lives, one of four men and one of six women free of COPD at the age of 55 years will have COPD develop.