This prospective randomized study demonstrated that the NCMIT program significantly improved completion of a 6-month HAV/HBV vaccine regimen when compared with the SI approach. Controlling for potential confounders, the NCMIT participants had almost 2 times greater odds of completing the HBV vaccination than that of the standard control. Although the SIT participants had 1.5 times greater odds of completing HAV/HBV vaccination than those of the standard control, these findings were not significant. The vaccination completion rates in both programs that incorporated tracking (NCMIT and SIT) were also higher than those in previous studies using financial incentives alone (Ompad et al., 2004
). A modest monetary incentive has been approved as an effective strategy to increase HBV vaccination coverage in hard-to-reach populations (Trubatch, Fisher, Cagel, & Fenaughty, 2000
). The findings suggest that targeted education and client tracking are also critical elements in supporting adherence.
Although the findings revealed statistically significant differences between the NCMIT and SI program (68% vs. 54%) and no significant difference in HBV vaccine completion between the SIT and SI programs, a question of clinical significance arises as the completion rate of the SIT participants (61%) is fairly close to the completion rate of the NCMIT at 68%. However, it is believed that clinical significance is present as the NCMIT is the only program found to be statistically different than the control program, and a cost–benefit analysis found the NCMIT program to be the most cost-effective program, as compared with the SIT and SI programs, for increasing HBV vaccine coverage among homeless adults (Greengold et al., under review
). Thus, it is believed that these findings are clinically different as well.
As guided by the CHSCP theoretical framework, a number of factors were associated with the completion of the HAV/HBV vaccine series. Nursing strategies (NCMIT) were found to be critical in enhancing completion among these homeless and marginalized persons at risk of hepatitis. In addition, as presented among the findings, a number of sociodemographic (age, gender, recruitment site, and years homeless), psychosocial (being partnered), and behavior (same-sex behaviors and attending self-help programs for drugs or alcohol) factors also were associated with the completion of the vaccine series.
In the current study, homeless persons who reported negative personal resources, such as fair or poor health, had higher odds of completing HBV vaccination. This finding is consistent with results from the study of adherence to tuberculosis chemoprophylaxis among homeless adults (Nyamathi et al., 2006
). In this population, poor perceived health status has been found to be associated with alcohol and drug use and with chronic health problems (Nyamathi et al., 2003
). Chronic illness, in turn, frequently leads to increased care seeking (Nyamathi et al., 2005
), which may produce higher vaccination adherence rates. Individuals with relatively poor perceived health status also may have been more motivated to get all their vaccine doses than were those with better health perceptions.
Also consistent with previous studies (Frangakis et al., 2004
; Lamagni, Hope, Davison, Parry, & Gill, 2001
), select sociodemographic factors predicted vaccine completion. In particular, the findings revealed that older homeless persons were more likely to complete the vaccine series than were younger homeless persons. One explanation may be that older people had been missed by many HBV vaccination campaigns and thus were more willing to participate in a free vaccination program. Alternatively, young drug users have shown poor adherence to preventive health behaviors (Seal et al., 2000
). In addition, with the implementation of routine HBV vaccination at entry to school and at birth, young people might perceive themselves to be at less risk of getting HBV, resulting in a lower likelihood of getting vaccinated. However, IDUs aged 15–29 years have the highest risk of HBV infection in the United States (Garfein, Vlahov, Galai, Doherty, & Nelson, 1996
). This study reveals a need to find additional strategies to improve HBV vaccine coverage in young male homeless populations; these might include, for example, incentives that appeal to men or social contacts.
It is not surprising that homeless adults who were younger and reported participating in self-help drug treatment programs were less likely to adhere to the vaccine regimen. Among homeless persons, youth are most at risk of HBV, HCV, and HIV because of methamphetamine and cocaine use, which are increasing rapidly in younger populations, including homeless persons (Santibanez et al., 2005
). These findings are also consistent with literature demonstrating that alcohol and drug users have poor completion rates for preventive therapy (Nyamathi et al., 2006
; Ompad et al., 2004
). Substance use, particularly methamphetamine and injection drug use, also might be one of the reasons newly homeless Whites were less likely than were African Americans to complete the vaccinations. Another explanation might be lack of social support networks, which may be helpful in adhering to the vaccination series. In addition, newly homeless Whites may not have built up sufficient trust with the minority program staff in the short study period, and lack of trust has been reported to be an important barrier to treatment completion (Altice, Mostashari, & Friedland, 2001
). The findings also suggest that newly homeless Whites may have different healthcare needs than those of chronically homeless persons. Designing culturally tailored programs for newly homeless White homeless persons might assist their rates of completion of the hepatitis vaccine series.
Homeless men were also less likely to complete the HAV/HBV vaccination series than were homeless women. As women are more likely to have used health services for reproductive healthcare, stronger healthcare interventions or greater incentives may be needed to achieve high rates of HBV vaccination completion among homeless men. Use of mobile vans to provide heath services also might result in higher completion rates in this vulnerable population.
Although the long-term goal is for homeless populations to achieve a 90% or higher HAV/HBV completion rates, strategies for successful outcomes emanate from the findings. These include targeting the groups least likely to complete the vaccine series with culturally competent and gender- and age-sensitive programs. These specific subgroups include the young and newly homeless persons and those who were least likely to seek substance use programs. Finally, considering accelerated time sequence HAV/HBV vaccine series may also be helpful (Keystone & Hershey, 2008
Surprising findings were that vulnerabilities common among the homeless, such as chronic homelessness, sleeping outdoors, alcohol and drug use, and mental health status, did not affect completion of the hepatitis vaccination series. In fact, nearly all homeless persons in the study reported that they intended to adhere to the vaccination protocol. Thus, service providers should not judge who among the homeless will be the most adherent to treatment programs.
The study sample was both a strength and a weakness. Participants were recruited from the Skid Row area of Los Angeles and represent a highly mobile and difficult-to-treat group. External generalizability of the findings to other difficult-to-treat groups and to homeless populations in other cities may be limited. Another limitation was that randomization by individual was not feasible because of concern about contamination across the programs. Although multilevel analyses could not be done because many participants were not sheltered and were highly mobile, sites were stratified into homeless shelter, drug recovery shelter, and outdoor locations before the randomization and the effect of recruitment site or area were further examined in the preliminary analysis. To help account for other contextual characteristics, a mixed-model logistic regression analysis was utilized using site or area as a random effect. An additional limitation was that sites were randomized to programs, whereas analyses were performed by individuals. Finally, control variables were based on self-report, which is subject to well-known biases.
The findings reveal that a culturally sensitive comprehensive program, which included nurse case management plus targeted hepatitis education, incentives, and client tracking, performed significantly better than did a usual care program with an added incentive. As the CHSCP demonstrates, factors which represented select sociodemographic factors (age, gender, and time homeless), resources (physical health), and behaviors (attendance at substance self-help programs) predicted vaccine completion. A program that included client tracking and incentives also promoted vaccine completion; nevertheless, the nurse-case-managed program had the highest odds of HBV vaccine completion compared with those of a standard control program in this study with homeless adults. This study provides additional good news for public health program planners and funders; when funding is limited, it is possible for more than half of homeless clients to complete the 6-month HBV vaccine series if hepatitis education, hepatitis vaccinations, and minimal client incentives are provided.