The Significance of Varicella Exposure History and Correlation with Serology among Patients with Inflammatory Bowel Disease: Presidential Poster

Abstract

Purpose: Varicella zoster virus (VZV) infection is a significant concern in immunosuppressed IBD patients with reports of severe, disseminated, and occasionally fatal infection. The European Crohn's and Colitis Organization (ECCO) guidelines on IBD immunization recommend using patient-reported varicella exposure history as an indicator to VZV immunity, and immunization of those with a negative exposure or vaccination history. Data on accurate recall of infection with corroborative serology are scarce. We analysed the significance of prior varicella exposure in predicting VZV seroprotection in IBD patients. Methods: We conducted a retrospective review of 220 consecutive patients attending our IBD clinic from October, 2012 to May, 2013. Data including patient demographics, disease phenotype, and prior VZV exposure (infection or vaccination), including VZV antibody titres, was obtained from electronic or case notes review. Ongoing medical therapy for IBD at the time of testing was also recorded. Results: Data for VZV exposure status and tests for VZV titres was available in 71 IBD patients (Crohn's disease n=39, ulcerative colitis n=32). Of these, 55% were females, the median age was 42 years (range 21-79), and mean disease duration was 8.7 years.Twenty-seven percent of patients were on no treatment, 24% were on aminosalicylates, and 49% were on effective immunosuppression. This included 16 (46%) patients on thiopurines, one (3%) on methotrexate, five (14%) on infliximab, two (6%) on adalimumab, three (8%) on infliximab + thiopurine combination, one (3%) on infliximab + methotrexate, six (17%) on corticosteroids, and one (3%) on infliximab + prednisolone. Two-third of patients (69%) were uncertain about a prior exposure to varicella; 28% gave a definitive history, and 3% stated no previous exposure. The overall prevalence of seropositivity for VZV IgG was 62/71 (87%), with 85% seropositivity in patients receiving immunosuppressive treatment. Despite definitive VZV exposure history, 10% patients were seronegative; these patients were on combined immunosuppressive therapy with infliximab and thiopurine. A total of 14% patients on immunomodulation were VZV IgG seronegative; 40% of these on bi-modal immunosuppressive therapy. Conclusion: A significant number of patients are seronegative, despite a positive history for varicella exposure, suggesting a loss of seroprotection possibly from immunosuppression. A strategy combining varicella exposure history with serology may identify history-positive yet seronegative individuals who merit vaccination, but arguably also identify history-negative yet seropositive individuals, resulting in a lower rate of unnecessary vaccination. There is an urgent need for more data, which could influence guideline development in this area.