This study validates a risk-based questionnaire for the identification of people with HCV infection in Gorgan central prison, Iran. Overall, 7.5% of residents and 4.6% of newly admitted inmates had a positive HCV antibody, which was a remarkably higher prevalence than the general population (5). Participants who were currently receiving OAT had a higher HCV antibody prevalence, compared to those with no history of OAT (11.4% vs. 4.0%). The history of drug use was the most accurate predictor of having a positive HCV antibody and RNA results, with respectively 95% and 97% sensitivity. This outcome indicates that in low and middle income settings with limited resources, HCV screening for people with no history of drug use could be skipped in correctional facilities.
The HCV antibody prevalence in Gorgan prison was much less than some previous Iranian reports (7% vs. 28%), but fourteen times higher than the general population (7, 9). Compared to a 2003 study, the prevalence of HCV antibody in Gorgan prison has decreased by 16%, which could be due to the implementation of several harm reduction programs in recent years (20). In Iran, HCV care models that are adapted for the specific needs of marginalized populations are emerging, including for people in custody; however, current interventions and harm reduction coverage are still not sufficient for breaking the cycle of transmission (21).
While the choice of a screening strategy is highly influenced by the expected prevalence and budget priorities, evidence on the different HCV screening approaches in low- and middle-income countries is scarce (18, 22). In resource-limited settings, risked-based screening is postulated to be of value for case finding among target populations (7, 19). However, the reliability of self-reported risk behaviors and the consistency with which the screening criteria are applied have shown to limit the early case detection ability (19, 23). Studies on the efficacy of a risk-based HCV strategy among marginalized populations are limited, and to date, case finding by surveys have been only done in high-income countries (18, 19). Previous studies have shown benefits for universal screening in correctional facilities, compared to the risk-based screening, which is in contrast to our findings (18, 24). A possible explanation could be that in Iran, no taboo exists around illicit drug use among the incarcerated population, which results in more reliable self-reported information (25). To avoid loss of treatment opportunity in prisons, the diagnosis and linkage to care for this hard-to-reach population should be obtained immediately upon admission (18, 26, 27). Therefore, tailored screening strategies should be developed to scale-up diagnosis among people in custody.
Evaluation of the HCV screening among target populations in resource-limited countries is limited (28). In this study, only 30% of the prison population had been tested for HCV before, from whom 59% were not aware of their test results, indicating the insufficiency of prison-based screening programs as well as poor HCV knowledge and post-test counseling. The history of HCV testing is similar to the previous estimates among people who use drugs in Iran (30% vs. 28%) (21). However, compared to people attending substance use treatment programs in the US, the rate of people who had never been tested for HCV in this prison was two-fold higher (69% vs. 30%) (29). Besides, self-reported information regarding the previous HCV test results with a high rate of false positives and negatives was unreliable (67% and 3%), which is a common observation among prison studies (30).
The history of drug use among all participants was remarkably high and very similar to the results from a study on 6200 Iranian inmates (71% vs. 74%) (3). The prevalence of drug use between residents and newly admitted inmates was almost similar (72% vs. 69%), which could be due to the fact that the majority of new inmates had a history of prior imprisonment (69%). Among all inmates with a history of drug use, 9% had a positive antibody that is 18-fold higher compared to the general population of Golestan province, where the study site is located (31). Moreover, participants who were currently receiving OAT represented a more vulnerable population for HCV infection compared to those with no history of OAT (11.4% vs. 4.0%). These results indicate that future HCV screening efforts should focus on people with history of drug use, particularly those who are attending or have a history of OAT. Comprehensive public health response to HCV in prisons should include tailored screening strategies and drug intervention programs such as OAT scale-up, together with assessment of health risk behaviors (21).
The history of drug use was the most sensitive question for predicting a positive HCV antibody test among all inmates (95%); this sensitivity was lower among newly admitted inmates compared to residents (89% vs. 96%), highlighting the fact that new inmates are more reluctant to disclose their drug use. Despite the high sensitivity of the drug use question, the other risk factors were low sensitive for case finding: among people with a positive HCV antibody test, 46% and 66% did not report any history of injecting drug use and sharing, respectively. Therefore, lifetime experience of injecting drug use and sharing needles is under-reported among people in prison. The unreliability of self-reported history of injecting drug use had been reported in other studies as well, which could be due to the existing reluctance of inmates to disclose their risk behaviors and face probable punishments in custody (32).
Due to the low sensitivity of the injection and sharing questions, and the low specificity of drug use question, we found no combination of self-reported risk factors that would be reliable enough to skip the HCV antibody and RNA testing in a cost-effective manner. It seems that risk-based screening could not become a replacement for HCV testing unless extensive efforts were made to remove the taboo against drug injection in societies. Also, despite the extensive harm reduction efforts in the recent decade, such programs are still inadequate in Iran, as well as many other countries (33).
The main strength of this study was its novelty in developing a low-cost strategy for countries with limited resources in the battle against HCV. However, our study had some limitations like using self-reported data, which its reliability has been questioned (19, 23). The main limitation is that because of the high costs of HCV RNA screening for all inmates, we assumed that our antibody kit has almost 100% sensitivity for diagnosing people with HCV infection. Thus, having a negative antibody is considered as negative RNA testing, which may slightly change our results due to the testing bias. However, in a previous study, we have shown that the sensitivity of our rapid screening test is almost 100% (34). Another limitation was that among newly admitted inmates with positive antibody (n = 19), 11 people were released before RNA testing. The venipuncture samples could not be collected daily, given limited capacity for RNA testing at the local laboratory and the lack of a fixed nurse in prison for obtaining blood samples. Participants were receiving HCV rapid testing upon admission daily, but those with a positive antibody were undergoing venipuncture after a few days, during which someone might be released. Despite newly admitted inmates, all of the prison residents with positive antibody tests underwent venipuncture and had data available. Also, the small number of female participants limits the generalizability of this study.