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* = Presenting author

P386 Durability of the anti-HBs titers after vaccination against Hepatitis B virus (HBV) in patients with Inflammatory Bowel Disease (IBD)

M. Chaparro*1, J. Gordillo2, E. Domènech3, M. Esteve4, M. Barreiro de-Acosta5, A. Villoria6, E. Iglesias-Flores7, M. Blasi2, J.E. Naves8, O. Benítez9, X. Calvet10, V. García-Sánchez7, J.R. Villagrasa11, A.C. Marín1, M. Ramas1, I. Moreno12, J.P. Gisbert1

1Hospital Universitario de La Princesa, IIS-IP and CIBERehd, Gastroenterology Unit, Madrid, Spain, 2Hospital Santa Creu i Sant Pau, Gastroenterology Unit, Barcelona, Spain, 3Hospital Universitari Germans Trias i Pujol and CIBERehd, Gastroenterology Unit, Badalona, Spain, 4Hospital Universitario Mutua de Terrassa, Gastroenterology Unit, Terrassa, Spain, 5Complejo Hospitalario Universitario de Santiago, Gastroenterology Unit, Santiago de Compostela, Spain, 6Hospital de Sabadell and CIBERehd, Gastroenterology Unit, Sabadell, Spain, 7Hospital Universitario Reina Sofía, Gastroenterology Unit, Córdoba, Spain, 8Hospital Universitario Germans Trias i Pujol and CIBERehd, Gastroenterology Unit, Barcelona, Spain, 9Hospital Universitario Mutua de Terrassa and CIBERehd. , Gastroenterology Unit, Terrassa, Spain, 10Hospital de Sabadell. Corporació Sanitària Universitària Parc Taulí and CIBERehd, Gastroenterology Unit, Sabadell, Spain, 11Hospital Universitario de La Princesa and IIS-IP , Preventive medicine unit, Madrid, Spain, 12Hospital Universitario de La Princesa and IIS-IP , Fundación de Investigación Biomédica, Madrid, Spain

Background

Among immunocompromised patients who respond to the HBV vaccine, clinically significant HBV infection has been documented in those who do not maintain anti-HBs concentrations > 10 IU/l.

Aims: 1) To understand the kinetics of the anti-HBs titers over time in IBD patients who have initially responded to the vaccination. 2) To identify predictive factors of negativization of anti-HBs titers over time.

Methods

This multicenter study included IBD patients vaccinated in the COMVI-B trial (EUDRA CT number: 2010-023947-14), where patients with negative HBV serology and without previous vaccination against HBV were randomized 1:1 to receive Fendrix ® or double doses of Engerix® at months 0, 1, 2 and 6. Patients with anti-HBs > 10 IU/l 2 months after the 4th dose were followed-up. Anti-HBs titers were then measured at 6 and 12 months. When anti-HBs titers were < 10 IU/l during the follow-up, they were considered negatives. Long-term maintenance of positive anti-HBs titers was estimated using Kaplan-Meier curves. Cox-regression analysis was performed to identify potential predictive factors for losing anti-HBs protective titers during follow-up.

Results

132 patients were included (median age 48 years, 55% males, 49% Crohn's disease and 51% ulcerative colitis). Thirty-one percent of patients were on immunomodulators, and 32% on anti-TNF drugs. Fifty percent of patients received each of the vaccines (Engerix® or Fendrix®). The cumulative incidence of negativization of the anti-HBs titers was 15% after 6 months and 21% after 12 months of follow-up. The incidence rate of negativization of the anti-HBs titers was 23% per patient-years of follow-up. In the multivariate analysis (adjusted by the patient's age and the treatment with thiopurines or anti-TNF drugs), to have had anti-HBs ≥ 100 IU/l (vs. < 100 UI/l) after the vaccination was the only factor that was associated with a lower probability of negativization of anti-HBs titers during the follow-up (HR=0.08, 95%CI=0.02-0.3, p<0.0001). The type of vaccine administered was not associated with a different risk of negativization of anti-HBs titers.

Conclusion

A high proportion of IBD patients with protective anti-HBs titers after vaccination lose them over time (approximately, 25% of patients per year of follow-up). The risk of losing protective anti-HBs titers is dramatically increased in patients achieving anti-HBs below 100 IU/l after the vaccination. Thus, anti-HBs > 100 IU/l should be the threshold to consider HBV vaccination success in IBD patients.