At what absolute lymphocyte count do you consider alternative/discontinuing DMT in a patient with MS on fingolimod (or other S1P modulator)?

I have asked this question for a long time, and get different answers. When a patient is hovering below 500, I start to wonder if it’s worth the long term risk/benefit. If they aren’t having infections and are young/healthy I usually leave them alone. If they’re getting older (50s and up) we have the conversation about switching, especially if developing risk factors for vascular disease and other comorbidities like DM. Switching has its risks too for rebound demyelination so it’s not always an ...