Increased prevalence of chronic obstructive pulmonary disease in a general population

Prevalence of COPD is increasing worldwide, and there is need for regularly updated estimates of COPD prevalence and risk factors.

In the Norwegian Hordaland County Cohort Study (HCCS), 1664 subjects aged 35-90 yrs answered questionnaires and performed spirometry in 2003-05. We estimated COPD prevalence and analysed risk factors for COPD with logistic regression.

In a previous study phase, prevalence of GOLD-defined COPD was 7%. Eight years later, corresponding prevalence was 14%. Seventy % of the subjects experienced respiratory symptoms. Only 1 out of 4 had a physician's diagnosis. Significant risk factors for COPD were sex, age, smoking habits and pack-years. Men had 1.7 (OR, 95% CI 1.2, 2.3) higher odds for COPD than women. Subjects above 65 yrs had 10.3 (OR, 95% CI 6.4, 16.5) times higher odds for COPD than subjects below 40 yrs. Heavy smokers had 4.2 (OR, 95% CI 2.6, 6.7) times higher odds for COPD than subjects with <10 pack-years. When compared with the previous study phase, age and smoking status had roughly the same associations with COPD prevalence. Educational level and male gender, on the other hand, had less effect on COPD prevalence in 2005 than in 1997, while pack years were more important in 2005 than in 1997.

Prevalence of GOLD defined COPD has increased from 7% to 14% in nine years. Although the risk factors remain the same, the strength of associations vary. There is still substantial under diagnosis in COPD, and better disease awareness and diagnostic routines are needed.