Characteristics of Foreign-Born Persons in the Swiss Hepatitis C Cohort Study: Implications for Screening Recommendations

Chronic hepatitis C virus infections in Switzerland in 2020: Lower than expected and suggesting achievement of WHO elimination targets

In this multi-method study, we investigated the prevalence of chronic infections with the hepatitis C virus (HCV) in Switzerland in 2020, and assessed Switzerland's progress in eliminating HCV as a public health problem by 2030 with regard to the World Health Organization (WHO) criteria targeting infections acquired during the preceding year ('new transmissions') and HCV-associated mortality. Based on a systematic literature review, the reappraisal of a 2015 prevalence analysis assuming 0.5% prevalence among the Swiss population and data from many additional sources, we estimated the prevalence among subpopulations at increased risk and the general population. For new transmissions, we evaluated mandatory HCV notification data and estimated unreported new transmissions based on subpopulation characteristics. For the mortality estimate, we re-evaluated a previous mortality estimate 1995-2014 based on new data on comorbidities and age. We found a prevalence of ≤0.1% among the Swiss population. Discrepancies to the 2015 estimate were explained by previous (i) underestimation of sustained virologic response numbers, (ii) overestimation of HCV prevalence among PWID following bias towards subgroups at highest risk, (iii) overestimation of HCV prevalence among the general population from inclusion of high-risk persons and (iv) underestimation of spontaneous clearance and mortality. Our results suggest that the WHO elimination targets have been met 10 years earlier than previously foreseen. These advancements were made possible by Switzerland's outstanding role in harm-reduction programmes, the longstanding micro-elimination efforts concerning HIV-infected MSM and nosocomial transmissions, little immigration from high-prevalence countries except Italian-born persons born before 1953, and wealth of data and funding.

HCV disease burden and population segments in Switzerland

BACKGROUND

Switzerland has made strides towards hepatitis C virus elimination, but as of 2019, elimination was not guaranteed. However, political interest in viral hepatitis has been increasing. We sought to develop a better understanding of Switzerland's progress towards HCV elimination and the profile of remaining HCV-RNA-positive patients.

METHODS

A previously described Markov model was updated with recent diagnosis and treatment data and run to generate new forecasts for HCV disease burden. Two scenarios were developed to evaluate HCV morbidity and mortality under the status quo and a scenario that achieves the Swiss Hepatitis Strategy Elimination targets. Next, an analysis was conducted to identify population segments bearing a high burden of disease, where future elimination efforts could be directed.

RESULTS

At the beginning of 2020, an estimated 32 100 viremic infections remained in Switzerland (0.37% viremic prevalence). Adult (≥18 years of age) permanent residents born abroad represented the largest subpopulation, accounting for 56% of HCV infections. Thirteen countries accounted for ≥60% of viremic infections amongst permanent residents born abroad, with most people currently residing in Zurich, Vaud, Geneva, Bern, Aargau and Ticino. Amongst Swiss-born HCV-RNA-positive persons, two-thirds had a history of IDU, corresponding to 33% of total infections.

CONCLUSIONS

In Switzerland, extra efforts for diagnosis and linkage to care are warranted in foreign-born populations and people with a history of drug use. Population-level measures (eg increasing the number of providers, increase screening) can identify patients who may have otherwise fallen through the gaps or avoided care because of stigma.

The Epidemiological Patterns of Hepatitis C in Lithuania: Changes in Surveillance from 2005 to 2018

Background and Objectives: Viral hepatitis C infection is an important public health concern worldwide because it is one of the major global causes of death and morbidity. The early identifi-cation of infected people, together with the provision of proper treatment, are the key strategies used in preventing HCV infection. However, data regarding the epidemiological patterns of hep-atitis C in Lithuania are limited. The aim of this research was to evaluate trends in acute HCV cases registered via the national surveillance system in Lithuania during 2005-2018. Materials and Methods: Incidence rates were calculated for data, stratified by gender, age group (0-24, 25-54, 55-74, and 75+), place of residence (urban or rural), and the Lithuanian county where the case was recorded. The crude incidence rate of hepatitis C was defined as the number of new infec-tions per 100,000 people during a one-year time period. A linear regression was applied to evalu-ate IR trends during the period of 2005-2018. Results: From 2005 to 2018, 572 cases of acute hepa-titis C were registered, and the incidence rate ranged from 2.03 cases per 100,000 people in 2005 to 0.55 in 2016. A statistically significant decreasing trend in the incidence rate was found during the study period (p < 0.0001). Almost 63% of the acute HCV infections recorded via the national surveillance system were in individuals aged from 25 to 54 years. Conclusions: Being male, aged between 25 and 34 years, and living in the city might be important factors for understanding the epidemiological patterns of HCV in Lithuania. Although the number of HCV cases recorded in Lithuania is decreasing, our country has one of the highest IRs compared to other European countries. This shows that a new approach to hepatitis C virus screening strategies is needed.

Very Low Hepatitis C Viral Loads in Treatment-naive Persons: Do They Compromise Hepatitis C Virus Antigen Testing?

BACKGROUND

Hepatitis C virus (HCV) antigen testing is less expensive than quantitative reverse-transcription polymerase chain reaction but has lower sensitivity for very low viral load (VLVL; HCV RNA ≤3000 IU/mL). Currently the benefits of antigen testing for screening are discussed, but data on prevalence and outcomes of persons with VLVL are scarce.

METHODS

We assessed prevalence and predictors of VLVL by logistic regression in treatment-naive participants in the Swiss Hepatitis C Cohort Study. We analyzed if the last viral load after VLVL was low, compared cirrhosis and mortality in persons with and without VLVL, and evaluated the number of samples with VLVL that were reactive by antigen testing.

RESULTS

We included 2533 treatment-naive persons with available quantitative HCV RNA testing results. Overall, 133 persons (5.3%) had a VLVL. Age 18-40 years, female sex, and human immunodeficiency virus coinfection were associated with VLVL. Of 72 persons with a viral load available after VLVL, 14% had a VLVL and 17% had spontaneous viral clearance. The prevalence and incidence of cirrhosis and mortality were comparable in persons with and without VLVL; all 24 persons with VLVL and cirrhosis had excessive alcohol consumption or immunosuppression. Overall, 33% of samples with VLVL were reactive by antigen testing.

CONCLUSIONS

The frequency of VLVL was low. Among the persons who would probably be missed by antigen screening, some had a favorable disease course, but some had immunosuppression and liver cirrhosis. The benefit of HCV antigen testing for screening may be limited by the risk of missing patients with severe liver disease.

Modelling the impact of different testing strategies for HCV infection in Switzerland

OBJECTIVE

Hepatitis C virus (HCV) infection is a major cause of liver disease. Since symptoms of chronic liver disease usually appear only late in the course of the disease, infected individuals may remain undiagnosed until advanced disease has developed. We aimed to investigate which screening strategies would be most effective to detect individuals unaware of their infection.

METHODS

We developed a mathematical model for HCV disease progression and compared the current practice of HCV testing in Switzerland with the following screening strategies: intensive screening of active injection drug users (IDU), screening of former IDU, screening of individuals originating from countries with high HCV prevalence, screening of individuals born 1951-1985 (birth-cohort) and universal screening. All screening interventions were considered in addition to a baseline scenario that reflected the current practice of HCV testing.

RESULTS

Within the first 4 years (2018-2021), every year, on average 650 cases were diagnosed in the baseline scenario, 660 with intensified IDU screening, 760 with former IDU screening, 830 with origin-based screening, 1420 with birth-cohort screening and 1940 with universal screening. No difference in liver-related mortality and incidence of end-stage liver disease between the screening scenarios was observed.

CONCLUSION

Our results suggest that only large-scale screening of the general population could substantially accelerate the rate of HCV diagnosis and treatment in Switzerland and other countries with similar epidemics. However, this implies screening of a large population with low prevalence, and may trigger considerable numbers of false-positive and borderline test results.

Impact of geographic origin on access to therapy and therapy outcomes in the Swiss Hepatitis C Cohort Study

Late diagnosis and treatment may increase morbidity and mortality among persons with hepatitis C virus (HCV) infection. We included all participants of the Swiss Hepatitis C Cohort Study (SCCS). We used unadjusted and adjusted logistic and Cox regressions to determine the association between the geographic origin of the participants and the following outcomes: antiviral treatment status; sustained virologic response; cirrhosis at enrolment; incident cirrhosis; loss to follow-up (LTFU); and mortality. The analyses were adjusted for sex, baseline age, education, source of income, alcohol consumption, injection drug use (IDU), HCV genotype, HIV or HBV coinfection, duration of HCV infection, time since enrolment, cirrhosis, (type of) HCV treatment, and centre at enrolment. Among 5,356 persons, 1,752 (32.7%) were foreign-born. IDU was more common among Swiss- (64.1%) than foreign-born (36.6%) persons. Cirrhosis at enrolment was more frequent among foreign- than Swiss-born persons, reflecting the high frequency of cirrhosis among Italian-born persons who acquired HCV between 1950 and 1970 in Italian healthcare settings. Although antiviral treatment coverage was similar, the sustained viral response rate was increased and the mortality was lower among foreign-vs. Swiss-born persons, with the lowest mortality in persons from Asia/Oceania. LTFU was more frequent in persons from Germany, Eastern and Southern Europe, and the Americas. In conclusion, in Switzerland, a country with universal healthcare, geographic origin had no influence on hepatitis C treatment access, and the better treatment outcomes among foreign-born persons were likely explained by their lower prevalence of IDU and alcohol consumption than among Swiss-born persons.

Trends in hepatitis C-related mortality in Switzerland

In order to accurately assess the burden of hepatitis C (HCV) and develop effective interventions, we must understand the magnitude and trends of mortality related to the disease. In the United States, HCV-related mortality is continuously increasing. We have no comparable data for Switzerland and other European countries, although a modelling study predicted a similar increase. We analysed time trends (1 January 1995-31 December 2014) in HCV-specific mortality rates in the Swiss general population using the death registry of the Swiss Federal Statistical Office (SFSO). We compared HCV-related mortality to HIV-related and hepatitis B (HBV)-related mortality. To determine potential under-reporting in HCV-related mortality, we probabilistically linked the SFSO data to persons who died in the Swiss Hepatitis C Cohort Study (SCCS). SFSO data showed that HCV-related mortality more than doubled between 1995 and 2003, but has since stabilized at ~2.5/100 000 person-years. Since 2000, HCV-related mortality has been higher than HIV-related mortality and was about fivefold higher in 2014. HBV-related mortality remained low at ~0.5/100 000 person-years. Of 4556 persons in the SCCS, 421 have died and 86.2% could be linked to the death registry. According to the SCCS, 133 deaths were HCV-related. HCV was not mentioned on the SFSO death certificate of 45% of these (n = 60/133). In conclusion, HCV-related mortality remained constant, possibly because quality of care was high, or because of under-reporting or because mortality has not yet increased. However, HCV-related mortality is now much higher than HIV- and HBV-related mortality, and under-reporting was common.