What can nephrologists learn from epidemiology?

During the last decade, epidemiology has played an increasing role in the study of renal diseases. In the fields of drug-nephrotoxicity and occupational renal failure, epidemiological research has made an important contribution. In recent years, the specific role of epidemiology in outcome research has gained recognition. Epidemiology is based on observations under real-life conditions using a representative sample of renal patients. Methods range from simple clinical observations and cross-sectional studies to case-control and prospective cohort studies. Contributions and limitations of the different epidemiological approaches are illustrated using the example of the nephrotoxicity of 5-aminosalicylic acid in patients with inflammatory bowel disease.