Estimating the incidence and prevalence of rare rheumatologic diseases : a review of methodology and available data sources

: Where the need for descriptive epidemiology is great, population based registries can be established, at considerable cost, to provide the desired data. In many instances, however, there may be existing data and information systems that provide morbidity information on sufficiently large, well defined populations to allow reasonable estimates of the incidence and prevalence of rare rheumatologic diseases.