Compliance with hepatitis B vaccination in 1175 heroin users and risk factors associated with lack of vaccine response.

AIMS: To investigate the feasibility of hepatitis B vaccination among heroin users, assessing adherence to the vaccination schedules and identifying factors associated with antibody response. DESIGN AND PARTICIPANTS: A large cohort study in nine public centres for drug users (PCDUs) in north-eastern Italy, with data collected between January 1989 and December 1998. A total of 1175 heroin users were selected and vaccinated with a recombinant vaccine using two schedules (0-1-6 months and 0-1-2 months).
FINDINGS: Eighty-eight per cent of patients completed the vaccination series and a protective antibody response occurred in 77% of subjects. Completion of the vaccination series was not related to the length of the vaccination schedule or whether the patient was still in drug abuse treatment at the end of the series, but was related strongly to the number of patients enrolled at each PCDU (Spearman correlation = - 0.93, P < 0.001). Four variables were significantly associated with lack of seroconversion in response to vaccination: older age (AOR = 0.91 per year, 95% CI 0.88-0.94, P < 0.001), 2-month vaccination schedule (AOR = 3.10, 95% CI 2.06-4.68, P < 0.001), HCV seropositivity (AOR = 0.69, 95% CI 0.47-0.99, P = 0.04), HIV seropositivity (AOR = 0.27, 95% CI 0.10-0.77, P = 0.01).
CONCLUSIONS: A large-scale, multi-site hepatitis B vaccination programme for heroin users proved feasible and effective. The factors associated with a lack of antibody response may be useful in identifying patients who would benefit most from routine post-vaccination testing, with booster doses for non-responders. These results suggest that hepatitis B vaccination for drug users should become a routine public health practice.