In order to give a response to the goal set by the WHO in 2016 for the elimination of HBV and HCV by 2030, this study was aimed at identifying the risk factors for these two types of BBD among one of the most important high-risk groups, i.e. incarcerated PWID. The results of this study showed that in 2015, the prevalence of HCV among incarcerated PWID was 67.53 times higher than the prevalence in the community (11), 4.7 times higher than the prevalence among prisoners (12), and 0.79 times higher than the prevalence among injecting drug users (10). In addition, the prevalence of HBV among incarcerated PWID was 2.73 times higher than the prevalence in the community (10), equal to the prevalence in prisoners (12), and 0.08 times higher than the prevalence among injecting drug users (10) in the same year. As a result of these comparison, the prevalence of HCV and HBV among injecting drug users was higher than that among the three groups of incarcerated PWID, prisoners, and community members. The higher prevalence of this disease among incarcerated PWID, than among prisoners and people in the community, can be justified as explained earlier in the introduction. However, the lower prevalence of the disease among this group than among injecting drug users may be attributed to the fact that although injections are done in prisons, but it is a prohibited practice; therefore, the frequency of injection, and in particular the practice of shared and non-sterile injection is less frequent in prison than in the community. Furthermore, prisoners may do not correctly express their injection status. However, the findings of a study by Falla et al. in Europe showed that the prevalence of HBV and HCV in prisoners is higher than that among injecting drug users (3). It highlights the significance of the fact that imprisonment results in the gathering of a large group of patients and provides a chance to implement health-related programs, including diagnosis, treatment, and prevention programs.
The simultaneous study of the prevalence of HBV and HCV in this study and other studies in Iran show that the prevalence of HCV is significantly higher than the prevalence of HBV among prisoners and drug users (10, 12), while at the community level, HBV is slightly more prevalent than HCV (10). It suggests that the transmission of HCV is more common than the transmission of HBV among high-risk groups. Hence, when resources and facilities are limited, it is recommended to give priority to HCV than HBV. In addition, in order to achieve the goal of eliminating hepatitis in the community, it is necessary to direct a large part of investment and health interventions toward HCV.
According to the results of this study, the prevalence of HCV among incarcerated PWID was 40.52%; although it is a remarkable figure, it is significantly lower than the figures reported for this group of people in other studies. The rate reported at a global level is 64% (18), and in the Snow’s study in Australia it is 47.4% (19). Moreover, according to Behzadifar et al. its rate in Iran is 53%. The observed difference may be attributed to the differences between the types of two studies. Behzadifar et al.’s study is a meta-analysis that covers studies published from 2004 to 2016, in which the highest prevalence rate is observed in the years prior to 2010 (20).
As the most important findings of this study, it was found that the prevalence of HCV among incarcerated PWID was associated with age 30 years old and over, being single, non-academic education, more than five years of imprisonment, history of piercing in lifetime, and history of extramarital sex. The association between HCV prevalence and age and lengthy imprisonment may be due to the fact that people aged 30 years and over and those with longer imprisonment terms are more likely than people younger than 30 and with shorter imprisonment terms to have long term contact with the high-risk groups and so they have a higher chance of exposure to risk factors. The relationship between HCV and being single can be attributed to the fact that married people have a kind of commitment and adherence to ethics that is less observed in single persons. The observed relationship between non-academic education and HCV may also be attributed to a lack of information and knowledge or a lack of social prestige that is observed in people with non-academic education; it is worth noting that academic education has a deterrent effect on socially negative behaviors. Piercing was also identified as a risk factor, which might be attributed to the needle shared and an incorrect sterilization. In addition, high-risk sexual contact was also among the most well-known ways of transmitting STD. Some of the identified risk factors in this study are more or less sporadically reported in the limited number of studies conducted on incarcerated PWID. Silverman-Retana et al.’s study in Mexico showed that the prevalence of HCV was positively associated with older ages (age over 40) and the frequency of imprisonment, while it had a negative relationship with high level of education and marriage (15). In a study by Dolan et al. in Australia, it was found that history of imprisonment and high level of education were associated with the prevalence of HCV among incarcerated PWID. Davoodian et al.’s study in Iran showed that the prevalence of HCV was associated with the length of the incarceration period (14).
According to the findings of this study, no risk factor for the prevalence of HBV among incarcerated PWID was identified. This is due to the low HBV infection among the studied people. This finding is consistent with the results of the Davoodian et al.’s study (14), however, the results of Daneshmand’s study in Iran indicated an association between HBV and the length of imprisonment (13). This controversy may be attributed to the differences in the setting of two studies. Daneshmand’s study was conducted among incarcerated PWID in a province (Isfahan) out of a total of 31 provinces of Iran, and the prevalence of HBV in the mentioned province was significantly higher (27.2%), while the prevalence reported in this study (2.46%) was achieved through conducting surveys in 19 provinces.