This study shows that the level of awareness regarding HBV in the Turkish-Dutch population is low. While HBV is a serious health problem in this community, over 70% of respondents have never thought about it in the past year. Knowledge about transmission and prevention of HBV is moderate, while there is especially little knowledge about the serious consequences of HBV. In this study, low HBV test- and vaccination rates are reported (15% and 3%, respectively). Test rates are even lower in people who are not married, or have lower levels of awareness and knowledge.
This study is the first research into awareness and knowledge regarding HBV and HBV-test rates in the Turkish community in the Netherlands, but it also has some limitations. Firstly, although we tried to stimulate response in various ways, the response rate was rather low (30.2%). This may be an indication of a lack of interest for the subject of hepatitis B which may jeopardize future participation in the intervention. The low response rate may also cause selection bias. Non-response analysis shows that non-respondents differed from respondents only with regard to gender (proportion female was 44% among non-respondents versus 54% among respondents), and not to age, migration generation and socio-economic status. Furthermore, the reported percentage of HBV carriers in our study is 9.5%, while we expected this to be between 2.6 - 4.8% [6
]. This indicates that persons affected by HBV might have been more willing to respond, and that actual levels of awareness and knowledge in the population might be even lower than presented in this study. Secondly, information bias might have occurred, as in our questionnaire we gave away some information about testing and vaccination. This may have resulted in higher knowledge-scores on the prevention items. Thirdly, self-reports of screening and vaccination may be affected by inaccurate recall or desirability bias. Fourthly, we cannot assume causality between the factors on the one hand and having been tested on the other, because of the cross-sectional research design. Last, it is not likely that multiple testing has biased the conclusions as we found a considerable number of significant differences between the groups, with p-values below 0.001.
We found low levels of knowledge regarding the consequences of HBV. Studies in Asian migrants in the USA found higher levels of HBV knowledge [25
]. One possible explanation is that HBV is an even more prevalent health problem in Asian populations, than in the Turkish population. Another is that knowledge may have been improved by health education activities in the country of origin or in the host country [19
]. As far as we know, this has not been the case for Turkish migrants coming to the Netherlands. These health education activities may also have influenced the test rates amongst Asian migrants in the USA (range 8 - 68%) [15
], which were considerably higher than the test rate we found amongst Turkish Dutch (14.7%).
Since 1989, national policy has prescribed HBV-screening for pregnant women. In our study, about 25% of the married females reported to have been tested. This proportion appears to be low in view of the fact that, based on demographic trend information in migrant women in the Netherlands, we estimate that in reality about 50% of all married females may have been tested during pregnancy [28
]. This would result in a total test rate of 22%, instead of the reported 15%. The women who underreported screening, are likely women who tested negative for HBV and are susceptible to the virus. As the aim of our intervention is both detecting HBV and protecting against HBV, we also target our intervention to these women in order to provide them with adequate preventive measures. Last, it is likely that screened women who appeared to be carriers are aware of having been tested, and therefore the underreporting does not affect the carrier rate.
Current screening guidelines also include source and contact tracing, which means that invitations for HBV-screening are extended to plausible source(s) and contacts of a notified HBV-carrier. This may explain the results of the regression analyses, which showed that the factors 'being married' and 'knowing a family member or friend with HBV' were (borderline) related to having been screened. The first time most of the Turkish-Dutch women will be tested for HBV is during pregnancy; which seldom occurs before marriage [30
]. The fact that knowing someone with HBV is related to previous HBV-testing has been shown in other studies [16
] as well as in our own. This may be due to HBV-affected family members or friends who are prompted to be tested themselves, or to the source and contact tracing.
Several studies found an association between higher age and having been tested [19
]. Although in our study we found a tendency that older people were more often tested, this relation was not significant. While other studies also found that the level of education, language proficiency, and level of health insurance were associated with previous testing, our findings did not confirm this. Almost everyone in our study had a health insurance, and this factor was not associated with having been screened. It is suggested that in areas with high levels of health-care coverage, the influence of being insured has less effect on actually being screened [26
]. This might also be valid for the level of education, which was high in our study.
This study shows that the Turkish population in Rotterdam has low levels of awareness and knowledge regarding HBV, and low rates of HBV-testing and -vaccination. While the national HBV-screening policy in the Netherlands covers mainly pregnant women and their contacts, the risk of HBV is present in the whole Turkish-Dutch population. In order to prevent HBV-transmission in adults, it would be useful to test people before they become sexually active. The findings in the present study show that the development of a health promotion intervention regarding HBV should raise awareness about the risk of HBV in this population, and particularly address the serious consequences of HBV.