I sent an email to CEO of PBC Foundation about legitimacy of the itching survey.
It is 100% legit but it comes from the GSK pharmacuetical agents. GSK are paying folks to complete the survey. The Foundation is promoting people to participate in it though. GSK is Glaxo Smith Kline.
Please, if you receive it in an email, feel confident to complete it.
Apparently, it is ongoing. The survey was sent to the Foundation members in the UK.