What parameters would you use to decide whether to stop hydroxychloroquine in a patient whose lupus is well controlled but is found to have a prolonged QT interval on routine EKG?  

This is an excellent question for which there is no one-size-fits-all answer. The first question is how prolonged the QT is, and if there is another drug they are on that is contributing to the prolonged QT. Obviously, it is important to avoid prescribing other medications that prolong the QT. It is...