[A common dilemma in medicine : fortuitous association or causal relationship ?].

Making the differential diagnosis between a simple fortuitous association and a true causal relationship is a challenge commonly encountered not only in epidemiology, but also in clinical practice. The nine criteria supporting a causal relationship published by Bradford-Hill in 1965 remain relevant, even if some amendments were proposed in recent years. The present clinical scenario illustrates this problem by analyzing the controversies concerning the relationships between hypercholesterolemia (LDL) and coronary heart disease on the one hand and between statin therapy and myalgia on the other hand.