Prior varicella zoster virus exposure in IBD patients treated by anti-TNFs and other immunomodulators: implications for serological testing and vaccination guidelines.

BACKGROUND: Varicella zoster virus (VZV) is a severe and preventable infection in immunosuppressed IBD patients. ECCO guidelines recommend VZV immunisation in patients with negative VZV exposure history. The value of patient-reported VZV exposure history for prediction of seropositivity in IBD patients remains unknown. Moreover, data on VZV immunity in adult IBD patients or accuracy of VZV serological testing under immunomodulator treatment is sparse.

AIMS: The primary aim was to determine the prevalence of seropositivity for VZV-IgG in immunomodulator-treated IBD patients. A secondary aim was to establish the value of patient-reported history of past VZV infection for prediction of immunity, to validate the current vaccination strategy.

METHODS: History of VZV-related illness was accessed by epidemiological questionnaire, and serological testing for VZV-IgG was performed. Serum anti-TNF medications levels were measured when applicable.

RESULTS: One hundred twenty one IBD (86% Crohn's disease, mean age 37 ± 12.8) patients were included in the study. Immunomodulator therapy was received by 87% (anti-TNFs- 71%) of the patients. Previous exposure to VZV was reported by 104 patients, and 97/104 (93%) were VZV-IgG seropositive. Seventeen patients, all seropositive, reported negative exposure history. The calculated positive and negative predictive values for the reported history of VZV exposure were 93% and 0% respectively.

CONCLUSIONS: Negative history of VZV exposure is a poor predictor of seronegativity. History-positive patients may still be seronegative and exposed to VZV infection. We suggest serological testing of all IBD patients with subsequent immunisation of the seronegative patients before initiation of immunosuppressive therapy.