What can nephrologists learn from epidemiology?

During the last decade, epidemiology has played an increasing role in the s tudy of renal diseases. In the fields of drug-nephrotoxicity and occupation al renal failure, epidemiological research has made an important contributi on. In recent years, the specific role of epidemiology in outcome research has gained recognition. Epidemiology is based on observations under real-li fe conditions using a representative sample of renal patients. Methods rang e from simple clinical observations and cross-sectional studies to case-con trol and prospective cohort studies, Contributions and limitations of the d ifferent epidemiological approaches are illustrated using the example of th e nephrotoxicity of Ei-aminosalicylic acid in patients with inflammatory bo wel disease.