Is COPD a rare disease? Prevalence and identification rates in smokers aged 40 years and over within general practice in Germany

Background. According to literature, COPD rates are high in spite of decreasing rates of main risk factors smoking and air pollution in developed countries. general practice is a good place to survey unbiased prevalence rates. Ten studies done in general practice over the last 20 years found prevalence rates among smokers between 13.1% and 92.1%. Objective. Prevalence and detection rates of COPD in smokers in German general practice. Methods. Twenty-eight of 34 invited and eligible GP surgeries in/around Duesseldorf, Germany, took part in the non-announced 2-day investigation of all smokers (≥40 years) who visited the surgeries. Lung function test by hand-held spirometer, peak flow, sympton part of St George's Respiratory Questionnaire, and data on smoking habits were used. GOLD criteria for COPD were employed. GPs had to give their diagnosis not knowing the test results. Results. Of 3157 patients attending the 28 surgeries, 538 were smokers. Four hundred and thirty-seven of these agreed to participate, 5 had to be excluded for medical reasons/unacceptable spirometry. Three hundred and ninety-eight patients have not been previously diagnosed with COPD or asthma. Thirty patients were disgnosed with COPD, making a prevalence of 6.9%, of which 15 patients were already known as having COPD. Conclusion. Our result of low prevalence differs strongly from all other studies in general practice. Considering our study design which avoids selection bias found in nearly all other studies (no pre-announcement, no self-selection of patients or GPs, high participation rate and testing all patients), we strongly believe that our findings reflect the current situation of COPD in German general practice.