TPO and rheumatoid arthritis: This pro-coagulant state involves increased plasminogen activator inhibitor-1 (PAI-1) levels, increased platelet apoptosis that causes a higher exposure of phosphatidylserine, and basal exposure of P-selectin in quiescent platelets that were significantly increased in TPO-RA-treated patients compared to pre-treatment levels or to untreated patients [138,139].