2. Post-Authorisation Efficacy Studies (PAES)
1. Scope of Post-Authorisation Efficacy Studies (PAES)
‘The aim is to enable regulators to request such studies when there are important questions about the efficacy of the medicine that can only be answered once the product is in general use, or when questions arise in the post-authorisation period.’ Dr Stella Blackburn, EMA, 2011
PAES are imposed in accordance with the Commission Delegated Regulation (EU) No 357/2014  . They mean an efficacy study which is requested by a Competent Authority based on at least one of the situations set out in this regulation.
The results from a PAES are considered important for complementing available efficacy data and must be submitted because they may have the potential to impact on the benefit-risk balance of the medicinal product or product information. PAES should  not lead to the premature granting of marketing authorisations - they cannot be used to compromise the initial level of evidence that is required to grant a marketing authorisation.
A PAES conducted post-authorisation can be imposed either:
- At the time of granting the marketing authorisation:
- when concerns relating to some aspects of the efficacy are identified and can be resolved only after the medicine has been marketed.
- After granting the marketing authorisation:
- when the understanding of the disease or the clinical methodology or the use of the medicinal product under real-life conditions indicate that previous efficacy evaluations might have to be revised significantly.
 COMMISSION DELEGATED REGULATION (EU) No 357/2014
 Legal requirements are identifiable by the modal verb “shall”. Recommendations that are not legal requirements are provided using the modal verb “should”.