Suspect surrogate end points

• Clofibrate reduced cholesterol in persons at risk for heart disease.  Lower cholesterol is associated with a lower risk for heart disease.  Unfortunately, patients who took clofibrate were more likely to die.
• Encainide reduces the number premature heart beats (PVCs) is persons who have had heart attacks.  PVCs are strongly associated with a higher risk of death after a heart attack.  Unfortunately, patients who took encainide after heart attacks were much more likely to die.  It is estimated that encainide caused thousands of excess deaths.
• Rosiglatazone lowers the glycohemoglobin level in persons with diabetes.  Diabetes is a risk factor for heart disease and lower glycohemoglobin levels indicate better diabetes control. Unfortunately, patients who took rosiglitazone had more heart attacks.

http://www.geripal.org/2013/04/surrogate-end-points-in-drug-trials.html