Hepatitis C seropositivity among newly incarcerated prisoners in Estonia: data analysis of electronic health records from 2014 to 2015

Hepatitis C virus (HCV) infection is an escalating global health issue and prisoners are emerging as an important high-risk group. HCV prevalence in this subpopulation ranges from 3 to 38% [1, 2]. Although this high burden of HCV is gaining notoriety and modern treatment can provide noticeable improvements in the health statuses of most patients, many countries still lack HCV prevalence data for high-risk groups. Epidemic patterns of HCV infection related to injection drug use persist in Europe. Understanding the risk factors for HCV infection among prisoners may inform HCV prevention and treatment intervention measures [2–5].

HCV prevalence is higher among prisoners than in the general population [2]. Intravenous drug use (IDU) is one of the major risk factors for HCV infection. The prevalence of IDU in prisons is ranging from 2 to 38% in Europe while the relevant percentage in the general population is estimated at 0.3% in the European Union and 0.2% in Australia. [6]. A metaanalysis showed that people who inject drugs (PWID) were about 24 times more likely to be infected with HCV than individuals in the general population in Europe [7]. IDU [8] and tattooing [9, 10] are the main risk behaviours for acquiring HCV infection in prisons.

Prisoners with human immunodeficiency virus (HIV) are more likely to be infected with HCV probably because of the similarity in the routes of transmission of these blood-borne infections [1, 3]. According to recent studies in Italian and US prisons, the HCV prevalence was more than four times higher among HCV-HIV coinfected patients than among those not infected with HIV (65.5–89.6% vs. 15.5–27.5%, respectively) [3, 11].

Another risk factor related to HCV infection is repeated incarceration [12, 13], an association that may be confounded by low socioeconomic status, poor access to health care, high-risk sexual behaviors and injection drug use [14].

In some studies HCV infection was observed more frequently in female inmates than in males. [1]. In part that may have been because the number of women in prison has grown and women prisoners are more likely than their male counterparts to have been incarcerated for drug offences [15] and to have serious drug-related health problems [16], including infectious diseases [17].

Direct-acting antivirals (DAAs) are relatively new and expensive, but cost-effective when well utilised as interventions for chronic hepatitis C, and preliminary results suggest that DAAs may eradicate HCV from the blood (sustained virological response). The effect of long-term treatment with DAA (hepatitis C morbidity and mortality) is yet to be convincingly demonstrated [18]. Still, ribavirin has been an integral component of treatment for hepatitis C virus (HCV) infection, and the safety profile of ribavirin is improved when co-administered with all-oral DAA combinations in the absence of interferon [19]. Several studies have shown that prisoners can be effectively treated for HCV infection [20–22], although treatment is administered less frequently to prisoners because of the cost of treatment, treatment often exceeding average prison stay combined with a lack of continuity of care, and unawareness of the HCV infected status of the prisoners [1].

Most HCV infected people are unaware of their condition [23]. Prisons may be a good venue to detect many of those cases. Although exact data are not available, each year, up to one million people with undiagnosed HCV infection may come into contact with the correctional system in the United States [24]. Strategies of case finding should be developed that are based on current infections rates and feasibility.

This study was carried out from 1 January 2014 to 1 January 2015. The term ‘newly incarcerated prisoner’ is used for all people, including adults and juveniles, detained during the investigation of a crime, while awaiting trial, after conviction, before sentencing and after sentencing, and incarcerated in one of the four Estonian prisons.

To our knowledge, this is the first study focusing on HCV prevalence and HCV treatment outcomes in the entire prison population of a European country. The studies that do exist are often restricted to individual prisons or subgroups of prisoners [2].

We found high HCV seropositivity rates (56%) among newly imprisoned individuals in Estonia. HCV seropositivity among newly incarcerated and tested prisoners (with either unknown HCV status or previous negative HCV test) was 35%. These prevalence figures are consistent with those from Italy (38%) [34] and Scotland (19%) [35], where available data suggest that HCV is highly prevalent among prisoners.

The risk factors for HCV seropositivity we observed (drug use, previous incarceration, HIVstatus, age) are in accordance with previous research [1, 2, 8, 14, 36]. According to previous studies in other countries, the main risk factor associated with HCV infection in prison populations is IDU [1, 2, 8, 37]. In our study, the odds for being HCV-positive were about three times higher among HIV-positive than HIV-negative prisoners. HIV and HCV share common routes of transmission, and are therefore expected to some extent co-infect the same individuals.

Previous incarceration has been significantly associated with HCV infection in studies from Australia, England, and Wales [36–38]. Multiple incarcerations were also found to be a risk factor for HCV seropositivity in our study. The contribution of HCV transmission in prison to the overall disease burden among PWID is difficult to document owing to uncertainties regarding precise date of infection and risk behaviours in the community (both prior to and post-incarceration). The role of prisons as a risk environment for the reinforcement, concentration and amplification of infections such as HIV and HCV has been suggested [39].

In our study, the seropositivity of HCV was higher among those with tattoos. However, this association was lost while adjusting for potential confounders. It is known that tattooing is common in prisons and jails [10] and prisoners who acquired their tattoos in prisons are more likely to be HCV-infected [1, 12, 34]. The risks and benefits of legal tattooing in prison should be discussed. Evidence from studies on the relationship between tattooing and HCV transmission in prisons appears to be mixed. Some studies report significant correlations [10, 36, 40] while others do not [41].

We found the presence of hepatitis C antibodies in 12 individuals (0.6%) who were HIV negative and had no records indicative of drug use. While we do not have data on other HCV risk factors (such as history of blood transfusion, high risk sexual behviour), all of the 12 prisoners had tattoos. Eight of them had acquired their tattoos while in prison during the Soviet era (personal communication with prisoners). One might speculate that the traditions of tattooing in prisons have changed (there appear to be fewer tattoos among more recent prison populations and drug using individuals).

Data on the relationship between HCV and gender in prison populations is also conflicting. In some studies, HCV infection was observed more frequently in incarcerated women than in incarcerated men. [1, 3]. Other studies did not find the same result [42]. In our study, after accounting for other risk factors, gender did not emerge to be associated with HCV seropositivity.

Screening strategies based on risk factors have traditionally failed to identify all patients at risk of infection, leaving a sizable proportion of patients unaware of their infection. We observed that a screening system for HCV case finding relying only on known risk factors misses a sizeable proportion of newly incarcerated individuals with HCV infection. The all-inclusive HCV testing strategy identified 37.7% more HCV infection cases among the newly incarcerated than would have been detected on the basis of known risk factors (drug use history, HIV infected status) screening.

In our study, the main HCV genotypes were 3a (n = 172, 44%) and 1b (n = 135, 35.2%). HCV genotypes have geographically distinct distributions. HCV genotype 1 and 3 infections are globally more prevalent than all other genotypes. Those genotypes, more commonly found in lower-income countries, account for a significant proportion of HCV cases worldwide [43]. Meyer et al. found that genotype 3 prevailed in prisoners from the independent states of the former Soviet Union [44]. Tyczyno et al. compared the HCV genotyping performed on Polish prisoners and hospital patients, and found that HCV genotype 3 prevailed in the prisoners (60.1%) and genotype 1 in patients at large (79.6%). This distinction is most probably due to the fact that genotype 3 is more frequent in PWID [45]. In Estonia, the following distribution of genotypes was documented among hospital patients: genotype 1b was found in 32% of the patients, 3a was found in 20%, 2a in 12%, and 1a/b (double infection) in 28% [46]. Among the Estonian prisoners tested for HCV genotypes nearly two decades later, we were unable to replicate the finding of 1a/b double infection occurrence.

The response to antiviral treatment in prisoners is similar to that of the general population [1]. Our study observed a 60% sustained viral response among treated prisoners. Importantly, this result does not differ from the treatment response reported from the community (in a hospital setting in Estonia) where a 60.3% sustained treatment response was achieved [47]. This suggests that acceptable HCV treatment outcomes can be achieved in prisons. There are clear advantages to HCV treatment in prison settings. In-prison, treatment provides the opportunity to access population groups for whom treatment options may be limited after release. Treatment in prisons occurs in controlled, directly observed settings, potentially achieving increased compliance and monitoring for side effects and complications [48, 49].

Our study has some strengths and limitations. A key feature of our study is the all-inclusive testing strategy and national coverage of the data collection. This is different from other, similar studies [11, 12, 14] conducted in the region because testing was offered and data were collected from all new prisoners entering all Estonian prisons. However, given the nature of the data used, we were unable to determine the frequency or duration of drug injection and, particularly importantly, distinguish between injecting and other types of drug use. Thus, some of the important details might have been lost. Importantly, we were unable to assess the impact of other potential HCV risk factors (such as sexual behaviour and previous blood transfusions, or surgery).

Case finding for HCV infection in prisons, HCV treatment and educational programmes to discourage high-risk behaviours might help curtail the rise in HCV infection in prison populations. Our study suggests that HCV treatment in infected inmates is feasible and the results (sustained viral response achievement) do not differ from that in the community.

Reducing HCV prevalence among prisoners has the potential to reduce the burden of disease in the general public in the community. When developing HCV screening strategies in prisons, policy-makers should consider the risk factors that we have highlighted in our study.

Our findings have several implications: they show that (i) universal HCV testing at prisonentry has the potential to increase the number of people who are aware of their infection, (ii) there is a need to scale up comprehensive HCV care to those infected. We believe that the results of this study might be applicable to other countries in the region that have witnessed injection drug use and related HIV epidemics in the late 1990s and early 2000s.