MO859: Factors Affecting Immune Response to Hepatitis B Vaccination Among Chronic Hemodialysis Patients in Saudi Arabia

Abstract

BACKGROUND AND AIMS It is well established that patients on chronic hemodialysis (HD) have an increased risk of hepatitis B virus (HBV) infection and reduced response to HBV vaccines compared with the general population.1 While advances in immunology and vaccinology have evolved several HBV vaccine modifications to enhance immunogenicity2; there is need to identify modifiable clinical factors that may help enhance response to HBV vaccines in the chronic HD population. This multi-center study aims to document the response to HBV vaccine among chronic HD patients across DaVita centers in Saudi Arabia and to identify the factors that independently affect the response of HD patients to the HBV vaccine. METHOD Patients eligible for HBV vaccination among our patient cohort who had received a full course of HBV vaccination (Engerix-B®, GlaxoSmithKline, United Kingdom) in all DaVita Clinics in Saudi Arabia were included in the analysis. We excluded patients who did not complete the vaccine protocol or had missing data and who were treated by immunosuppressive drugs. Levels of the antibody to the surface antigen (anti-HBs) were measured about 2 months after the last dose of the vaccine using enzyme-linked immunoassay methods. The age (in years), dialysis vintage, hepatitis C infection, diabetic status, mean albumin, parathyroid hormone (PTH), ferritin and hemoglobin levels 2 months prior to and during the 6 months of completing the vaccination protocol were recorded. Response to HBV vaccine was recorded as ‘no response’ if anti-HBs was < 10 mIU/L; ‘weak response’ if the anti-HBs level is between 10–99.9 mIU/L, and ‘good response’ when ≥ 100 mIU/L. Univariate and multivariate ordinal logistic regression models were used to identify the factors independently associated with response to HBV vaccine. RESULTS We had 509 patients with a mean age of 54.1 ± 15.1 years, 252 (49.5%) being female. Diabetes mellitus was the etiology of kidney failure in 60.5% of the patients. Most (91.1%) had concomitant hypertension and 4.3% were positive for hepatitis C virus infection. BMI was at least 30 kg/m2 in 26.1% of the study population. Immune response occurred in 374 {73.5%, [95% confidence interval (95% CI) 69.4–77.3%]}. Good response occurred in only 53.1% (95% CI 48.6%–57.4%). The factors independently associated with response to HBV vaccination were age, mean albumin, PTH, ferritin levels and BMI (Table 1). Diabetic status and Kt/v did not predict vaccine response. CONCLUSION A complex interaction of inflammatory markers, nutritional status, bone mineral disease parameters affects the response to HBV vaccines. Improving chronic dialysis patients’ albumin and PTH levels may increase the likelihood of achieving a good response to HBV vaccines.