Mechanisms of disease

5. Clinical Endpoints

To ensure that the medicine has the desired effect on the disease, clinical trials with patients who have the disease are conducted. Again, it is not enough to ensure that the target activity is changed, since the symptoms of the disease could still persist. It is therefore important to determine the effect of the treatment in the patients. These are measured and known as ‘clinical endpoints’ as defined in the trial protocol. Clinical endpoints could be:

• the number of bone fractures in a given period - after starting treatment for ‘osteoporosis’ (a condition where patients have fragile bones)

• the length of migraine attacks - after the medicine for migraine has been given
• blood factors important for oxygen transport returning to normal levels - after treatment for anaemia has started
• number of verified ‘acute myocardial infarctions’ (heart attacks) or even death - in patients receiving preventative treatment for thickening of the arteries (arteriosclerosis).

It is important that the endpoints measured are objective (i.e. unbiased) and allow for quantification (i.e. they are countable). When an effect is seen by such measurements, the Regulatory Authorities involved in granting the Marketing Authorisation of the medicinal product can be sure that the medicine is effective. Thus, it is only through the conduct of clinical trials that evidence for the benefit of a medicine can be provided.  

The other, and equally important aspect, is the safety of the medicine. Based on these two factors the benefit (efficacy) and risk (safety) of a medicine can be evaluated - this is called the benefit-risk relationship. The medicine will only be allowed on the market if the benefits are higher than risk, i.e. there is a positive benefit-risk relationship.