Misleading hepatitis B test results due to intravenous immunoglobulin administration: implications for a clinical trial of rituximab in immune thrombocytopenia
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abstract
BACKGROUND: Rituximab may cause reactivation of hepatitis B virus (HBV) even in patients with remote HBV infection. Thus, the presence of hepatitis B core antibodies (anti‐HBc) was an exclusion criterion for a randomized trial of rituximab for patients with immune thrombocytopenia. A high seroprevalence of anti‐HBc observed among patients screened for the trial prompted this substudy to investigate for an association between anti‐HBc seropositivity and exposure to intravenous immunoglobulin (IVIG).STUDY DESIGN AND METHODS: This was a retrospective case‐control study that was a substudy of a randomized controlled trial.RESULTS: Of 24 trial participants screened at one center, 11 (45.8%) were anti‐HBc positive and of those, 10 (90.0%) had received IVIG in the preceding 4 weeks. Of 13 seronegative patients screened, five (38.5%) had received IVIG (odds ratio, 16; 95% confidence interval, 1.5‐166.1). Seven (70%) of 10 seropositive participants subsequently reverted to negative upon repeat testing. Serial testing before and after IVIG (n = 2) demonstrated transient anti‐HBc that lasted for up to 11 weeks after the last dose of IVIG. Samples from three of five different IVIG products were found to contain anti‐HBc.CONCLUSIONS: Passive transfer of anti‐HBc from certain IVIG products may lead to misinterpretation of hepatitis test results with implications for treatment and clinical trial eligibility. To avoid misleading test results, anti‐HBc should be measured before or 3 months after IVIG administration; alternatively an IVIG product known to be free of anti‐HBc should be used.
