Les enseignements apportés par les registres de la polyarthrite rhumatoïde

Observational research from registries in rheumatoid arthritis (RA) has been developing over the past years and has certainly contributed to advance the field. We will summarize the benefits of registries by giving some examples of notable contributions from this line of research. We will then review the main limitations of observational research and illustrate the problems of confounding and selection bias. Finally, we will discuss the possibilities opened by combining registries.