Contribution of clinical epidemiology to evidence-based nephrology

Improvement of modern medicine does not make day-to-day practice of nephrol ogy easier. Decision-making remains difficult, often requiring numerical, p robabilistic approach. Contribution of clinical epidemiology to evidence-ba sed nephrology is not limited to randomised-control led trial. The concept of natural history: spontaneous evolution without treatment, has been devel oped in epidemiology to describe diagnosis and prognosis of diseases. For e xample, in IgA nephropathy, it allowed to measure the prognostic significan ce of gross hematuria or to design classification of end-stage renal failur e, Epidemiologic studies needs appropriate designs, representative samples and correct methods of analysis. Like other medical research, epidemiology has some important methodological limits that must be taking into account. Practising evidence-based nephrology improves confidence in management deci sions.