Approaches to estimate the population-based incidence of community acquired pneumonia

In Germany the estimation of a population based annual incidence of community acquired pneumonia (CAP) in adults has been referred to the denominator problem. To estimate a population based annual incidence of CAP in an urban German area we compared the incidence estimated on four different approaches.

We estimated the annual incidence on the basis of the covered population of sentinel practices from Luebeck participating in the German competence network CAPNETZ. We estimated the incidence on the basis of a population based survey, on the basis of the mortality and lethality in Luebeck, and on the basis of data of the regional Association of Statutory Health Insurance Physicians ("Kassenärztliche Vereinigung (KV) Schleswig-Holstein").

The annual incidence of CAP in Luebeck was 3.7/1000 inhabitants (95% confidence interval (CI) 2.4-5.5), 6.0/1000 inhabitants, 8.7/1000 inhabitants (95% CI 8.2-9.1), or 10.1/1000 inhabitants (95% CI 9.6-10.5) depending on the approach of estimation. According to this, in Germany we would expect 400,000-680,000 new CAP cases per year.

The true incidence of CAP in Luebeck might range between 3.7 and 10 per 1000 inhabitants. Comparisons with the rates in the literature are difficult due to the differences in the applied methods.