Prevalence of asthma and COPD in general practice in 1992: has it changed since 1977?

BACKGROUND: Asthma and COPD are common diseases of the airways which are mainly diagnosed and treated in general practice. AIM: Various studies have reported an increase in the morbidity of asthma and COPD. There are two possible reasons for such an increase. The first is an apparent increase caused by using different criteria in defining asthma/COPD, and by increased awareness of the disease by doctors and patients. The second is a real increase caused by an increase in the prevalence of airway pathology. The aim of this study was to determine the cause of the observed increase in morbidity. METHOD: In 1977, a sample of 2328 adults from the general population were screened for asthma and COPD. Those screened were then divided into five sub-groups (grades 1-5), according to severity of: (1) respiratory symptoms; and (2) loss in FEV1. The number of patients who were not known to the general practitioner prior to the screening as having asthma or COPD grades 1-5 were also assessed. In 1992, we studied a different sample of 1184 adults of the general population in the same area. We used the same criteria as in 1977 to analyse our results. The number of patients not known to the general practitioner prior to the screening was also studied. RESULTS: The overall prevalence (grades 1-5) of asthma and COPD has increased from +/- 19% in 1977 to +/- 31% in 1992 (range 21-42). The main reason for this is an increase in prevalence of very mild to moderate asthma and COPD (grades 1-3) from 17% in 1977 to 27% in 1992. The prevalence of severe cases (grades 4-5) increased from 2% in 1977 to 4% in 1992. In 1992, around 65% of the patients were not known to the general practitioner as having any grade of asthma or COPD. This was only slightly lower than the 72% in 1977. All patients with a severe disease (grade 5) were known to the general practitioner. CONCLUSIONS: There is a real increase in the prevalence of asthma and COPD, caused predominantly by an increase in the number of mild cases. The percentage of patients not known to the GP were predominantly mild cases.