Primary MyelofibrosisJanus KinasesPyrazolesJanus Kinase 2SplenomegalyJanus Kinase 1Protein Kinase InhibitorsMyeloproliferative DisordersClinical Trials, Phase III as TopicIntention to Treat AnalysisDrug ApprovalThrombocytopeniaClinical Trials, Phase I as TopicPolycythemia VeraClinical Trials, Phase II as TopicSpleenOrgan SizeFollow-Up StudiesTreatment OutcomeDouble-Blind MethodQuality of Life