Understanding if drugs that treat Psoriatic Arthritis (PsA) can work once people have tried lots is a priority to people living with PsA. We don’t have much information, and it may be affected by how people are included in research, meaning we can’t trust the results. We re-analysed data from a study showing that people can still respond to drugs after they have had 4 or more using statistical methods and data from routine clinics. The results confirmed people can still respond after 4 or more drugs but also that the original study underestimated how well people respond to their first drug.