biostudies-literatureUnknown8(4)Fischer K<h4>Background</h4>Patients with hemophilia have a life-long risk of developing neutralizing antibodies (inhibitors) against clotting factor concentrates. After the first 50 exposure days (EDs), ie, in previously treated patients (PTPs), data on inhibitor development are limited.<h4>Objectives</h4>To report inhibitor development according to factor (F)VIII or FIX concentrate use in PTPs with severe hemophilia A and B.<h4>Methods</h4>Inhibitor development in PTPs was collected since 2008 from 97 centers participating in European HAemophilia Safety Surveillance. Per concentrate, inhibitors were reported quarterly and the number of PTPs treated annually. Incidence rates (IRs)/1000 treatment years with 95% CIs were compared between concentrate types (plasma derived FVIII/FIX, standard half-lifResearch and practice in thrombosis and haemostasis102461https://www.ebi.ac.uk/biostudies/studies/S-EPMC11255940biostudies-literatureInhibitor development according to concentrate after 50 exposure days in severe hemophilia: data from the European HAemophilia Safety Surveillance (EUHASS).PMC11255940Garypidou VLanger FBrons PCastaman GOldenburg JSchinco POrtega ISAgnelli GHollingsworth RKatsarou OAnzej Doma SMartinez LSLester WMiesbach WAraujo FGrainger JGatt ACarbonero DLaros-van Gorkom BKaczmarek RTosetto AFontana PShapiro SFischer KLaffan MCatherine BKavakli KAndrew PVerhamme PSalta SMorais SHermans CMatthias MLeebeek FWWindyga JAy CLehtinen AED'Oiron RCatarino CGouw SCAires AZanon EOliveri MLissitchkov TMakris MMcdonald VPalomo Bravo ARocino AHarroche AAustin SNemes LKlamroth RHay CBenson GNomikou EBella MNolan BHolmstrom MMakelburg ALambert TBuehrlen MSchmugge MBlatny JZulfikar BSusen SThynn Thynn YPoulsen LHDe Crisotofaro RTalks KPlatokouki HBiron CKomrska VPaolo RPinto FAntoniades MO'Connell NBaghaei FEconomou MDargaud YPeyvandi FKampmann PSerban MBonanad STagliaferri AEuropean HAemophilia Safety Surveillance (EUHASS) participantsLejniece SPenka MSchutgens RFraga CDavydkin IGailiute NKhan MBatorova ASpannag PLassila RPayne JAstermark JMale CFarrelly CMaclean RfalseInhibitor development according to concentrate after 50 exposure days in severe hemophilia: data from the European HAemophilia Safety Surveillance (EUHASS).<h4>Background</h4>Patients with hemophilia have a life-long risk of developing neutralizing antibodies (inhibitors) against clotting factor concentrates. After the first 50 exposure days (EDs), ie, in previously treated patients (PTPs), data on inhibitor development are limited.<h4>Objectives</h4>To report inhibitor development according to factor (F)VIII or FIX concentrate use in PTPs with severe hemophilia A and B.<h4>Methods</h4>Inhibitor development in PTPs was collected since 2008 from 97 centers participating in European HAemophilia Safety Surveillance. Per concentrate, inhibitors were reported quarterly and the number of PTPs treated annually. Incidence rates (IRs)/1000 treatment years with 95% CIs were compared between concentrate types (plasma derived FVIII/FIX, standard half-lif2024-01-01T00:00:00Z2024 May2025-04-18T13:11:51.163Z2025-04-06T22:45:39.314ZS-EPMC112559403902665910.1016/j.rpth.2024.102461