Hepatitis-B Vaccination, Behavioral Cognitions, and Changing Risk Behaviors among a Drug Using Population: Findings from a Cluster Randomized Controlled Trial

Geetanjali Kamath, The University of Texas School of Public Health


Drug users are at increased risk of bloodborne infections like Hepatitis B, Hepatitis C and HIV due to injecting drugs, sharing injecting equipment, transactional sex, and failure to use condoms. Females may have higher risk of exposure through less control over sexual practices and passive injection. Hepatitis B vaccine coverage among drug users is low, and most known reasons are non-modifiable. Identifying individual-level behavioral cognitions is important for developing interventions to increase vaccine adherence. Interventions are also needed to reduce their risk of infection via both injecting and sexual routes. A sample of 1260 not-in-treatment, Houston-based drug users participated in a randomized controlled trial that offered a 3-dose hepatitis B vaccine by standard or accelerated schedule; and either an enhanced or standard behavioral intervention. At baseline, they answered questions on their thoughts, beliefs, and attitudes about hepatitis B infection and vaccination. Factor analyses were conducted on data from 626 participants in the standard vaccine schedule arm to identify latent behavioral cognitions underlying participants’ responses. The relationship between cognitions and vaccine adherence was assessed in a structural equation model (SEM); for all participants, and with separate models by gender and drug injecting status. Participants also answered questions on injecting and sexual risk behaviors at 0, 6, 12, 18, and 24 months; responses were weighted and summed to obtain injecting and sexual risk behavior scores. The effect of the enhanced behavioral intervention on risk scores over 24 months was tested using generalized linear regression. Factor analyses of 18 questions identified 6 behavioral cognitions: attitudes, self-efficacy, fear/ worry, outcome expectations, perceived norms and risk perception. ‘Attitudes towards vaccination’ was predictive of vaccine adherence among all participants [AOR=1.18;95%CI=0.93-1.51;p=0.18] and never-injectors [AOR=1.33,95%CI:1.00-1.77,p=0.047]. ‘Perceived norms’ [OR=1.80,95%CI:1.03-3.15,p=0.04] and ‘risk perception’ [AOR=1.40,95%CI:1.06-1.83,p=0.016] predicted vaccine adherence in females and injecting drug users respectively. The enhanced behavioral intervention group had significantly lower adjusted mean injecting risk behavior scores over 24 months compared to the standard behavioral intervention group in the entire sample [20% reduction, RR=0.79; 95%CI=0.70,0.91; p=0.00] and among men [28% reduction, RR=0.73; 95%CI=0.63,0.84; p=0.00]. Tailored, culturally-sensitive interventions should highlight the evidence on the benefits of vaccines while eliminating misconceptions on their adverse effects. Social support should be incorporated in interventions targeting female drug users. Further research is encouraged to develop valid and reliable measures for vaccine-related cognitions. The enhanced behavioral intervention succeeded in reducing injecting risk behaviors, but not sexual risk behaviors over 24 months of follow-up. Substance abuse programs should incorporate education on safe injecting practices and deliver reminders at 6-month intervals post-intervention.^

Subject Area

Biostatistics|Behavioral sciences|Virology|Epidemiology

Recommended Citation

Kamath, Geetanjali, "Hepatitis-B Vaccination, Behavioral Cognitions, and Changing Risk Behaviors among a Drug Using Population: Findings from a Cluster Randomized Controlled Trial" (2017). Texas Medical Center Dissertations (via ProQuest). AAI10271627.