Reuters Health Information (2010-10-27): Accelerating HBV vaccine boosts adherence for IDUs
Accelerating HBV vaccine boosts adherence for IDUs
Last Updated: 2010-10-27 17:05:25 -0400 (Reuters Health)
NEW YORK (Reuters Health) - Accelerating the hepatitis B virus (HBV) vaccination schedule can increase the number of injection drug users (IDUs) who receive all three doses, new research shows.
The quicker schedule didn't make much difference in the overall study population of drug users - but the finding that it improved adherence in the IDUs is still very worthwhile, the investigators say. While targeted immunization strategies have helped slow the spread of hepatitis B in the US, immunization rates among IDUs remain very low. At least 20% of HBV infections occur in IDUs, according to lead author Dr. Lu-Yu Hwang of the University of Texas Health Science Center at Houston and colleagues.
Their new study tested two different approaches for boosting adherence to the multi-dose vaccine: a behavioral intervention and an accelerated dosing schedule. (The trial results will influence the design of future efficacy trials of hepatitis C or HIV vaccines among drug users, the authors say.)
The researchers enrolled 1,260 active drug users - including 378 (30%) who were IDUs -- in two urban neighborhoods, assigning them to four different arms of the trial. Volunteers who enrolled in odd-numbered months received the vaccine on the standard schedule, i.e., at 0, 1 and 6 months. Volunteers signing up in even-numbered months got the accelerated protocol, i.e., doses at 0, 1 and 2 months.
After neighborhood-level cluster randomization, subjects received either a standard behavioral intervention (with information on HIV awareness and prevention) or an enhanced intervention intended to increase adherence to the hepatitis B vaccine.
Study participants received $30 at their initial visit, and $20 for each follow-up visit (including check-ups at 12, 18 and 24 months), according to a report of the study published online October 11th in the Journal of Infectious Diseases.
Overall, three-quarters of the study population received all three doses of the vaccine, with no difference between the standard- and accelerated-dose groups. But among IDUs, the adherence rate was 75% with the accelerated schedule vs 66% with the regular schedule (p = 0.04). There was no difference among non-IDUs.
The enhanced behavioral intervention had no effect on improving adherence, the authors report.
On multivariate analysis, the following factors were associated with adherence to all three doses in the total study cohort: African-American race (adjusted odds ratio 1.56), current alcohol use (aOR 1.38), and older ages. People who lived on the street or used speedball (an injected mix of cocaine and heroin) were significantly less likely to complete the schedule.
At six months, the seroprotection rate among those in the accelerated group who had received all three doses was 62%. At that point, subjects in the standard schedule group had not yet received their third dose; in that group, the seroprotection rate was 49%. This suggests, the researchers say, that accelerated schedules can provide "additional months of protection" as well as improving adherence.
"The results of this study indicate that providing monetary incentives at each visit, free vaccinations, and a shorter vaccination schedule may encourage adherence, particularly among the highly at-risk group of IDUs," Dr. Hwang and colleagues write. "Straightforward payment for the receipt of immunizations may be not only ethically sound but also an economically sensible way to use limited public health resources."
J Infect Dis 2010;202:1500-1509.