Why does every hairloss study need a new control group?

[Dimitri001]

After god knows how many years of hiarloss research which featured control groups, don't we at this point know how the TAHC of Androgenetic Alopecia sufferers who receive placebo for x period of time behaves? Why does every new study need to recruit another group of people and give them nothing and track how their TAHC changes? Now, of course, studies vary in their length, but surely there have been a sufficient number of long lasting studies with control groups that could cover almost any length of time and for which raw data is available which could serve as historic controls. Isn't this just an unnecessary expense?

 

[pegasus2]

The control group has to be from the same population as the treatment group, and the growth must be measured over the same period of time due to seasonal variations in shedding, which also varies by location. The method and examiner must be the same as well to ensure uniformity. In practice we see wildly different numbers for control hair count across studies.

 

[rrbelloff]

No, control groups are always useful when testing any new drug, change in dosage or combo with other drugs.

 

[Kojakjr]

You need valid random scientific studies to get FDA approval which would be worth $millions. So a control group is automatic.