5. Unblinded

An open-label trial is one in which no blinding is used and all parties are aware of the allocation of participants to treatment groups.

Open-label trials may be used:

  • For surgical procedures*.
  • When changes in lifestyle are required.
  • When endpoints are objective and cannot be interpreted in different ways.
  • For studies in life-threatening situations.
  • In post-marketing surveillance.
  • When ethical considerations do not permit blinding.
  • When no control group can be used. 
* It should be noted that surgical procedures can be blinded but are extremely difficult to blind. This is very hard especially if participants can be compared.