The European Journal of Public Health Advance Access originally published online on June 22, 2006
The European Journal of Public Health 2007 17(1):69-74; doi:10.1093/eurpub/ckl088
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International perspectives |
Measurement and reporting of burden of disease for hepatitis A: results of the EUROHEP.NET feasibility survey
P. Bonanni, S. Boccalini, A. Bechini and on Behalf of the EUROHEP.NET Team*Department of Public Health, University of Florence Italy
Correspondence: Prof. P. Bonanni, MD, Department of Public Health, University of Florence, Viale Morgagni 48, 50134 Florence, Italy, tel.: +39 055 4598511; fax: +39 055 4598935, e-mail: paolo.bonanni{at}unifi.it
Received August 25, 2005, accepted May 18, 2006
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Abstract |
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Background: European countries use a wide variety of surveillance systems and prevention measures for viral hepatitis. Each system is adapted to the local situation and an overview was never mapped out at European level. The EUROHEP.NET Project is a European Commission-funded feasibility study for a future network on surveillance and prevention of vaccine-preventable hepatitis. We analysed the measurement and reporting of burden of disease for hepatitis A (HA) and B (HB) in the participating countries. Methods: Twenty-eight countries were invited to participate in this study. An online survey was available from the project’s website (www.eurohep.net). The questions concerned the organisation of the surveillance system, case definition, burden of disease, epidemiology, and vaccination strategies. The responses on data sources and the numeric data related to burden of disease for HA for the period 1997–2001 were analysed. Results: Twenty-two countries completed the survey for hepatitis A. Data on total number of hospitalisations and deaths were available from 17 and 18 countries, respectively, although sometimes not complete. Data on hospitalisation days, number of liver transplants and proportion of these due to HAV were often not available. Conclusion: Surveillance systems on burden of disease for hepatitis A show a wide diversity among the participating countries. The introduction of a standardised system of data collection at the European Union level according to ICD-10 but respecting the local current practices is a primary need, especially for data that should be collected in all countries, like hospitalisation and mortality. A link to surveillance databases is also strongly recommended.
Keywords: burden of disease, feasibility study, hepatitis A, networks, surveillance
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Introduction |
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The circulation of hepatitis A virus (HAV) has substantially decreased in the last decades with the improvement of sanitation in many European Union countries.1,2 In areas with high social and healthcare standards, the main risk factors responsible for the present incidence of HAV disease are the increasing international travel to and migration from endemic countries.3–6 These factors, together with the increasingly wider importation of exotic foods, the widespread habit to send infants and young children early to daycare centres,7,8 and the attendance of darkrooms or saunas by homosexuals9–13 are the most important reason of several outbreaks described in Europe in the last decade. In addition, the decline in the incidence of HAV infection has generated an increasing proportion of susceptible people, thus creating the condition for outbreaks to occur also in adults, who are more likely to suffer from severe disease.14–16 Therefore, discussions on the implementation of alternative hepatitis A immunisation strategies have become the subject of a lively debate.
The countries participating in the EUROHEP.NET Project on Surveillance of Vaccine Preventable Hepatitis make use of a wide variety of surveillance systems and prevention measures for viral hepatitis A and B at national, or even subnational, level in their communicable disease surveillance system; each system is adapted to the local situation and was never mapped out at European Union level. Therefore, the existing national data on viral hepatitis burden of disease cannot be simply combined.17
Integrated disease surveillance and prevention networks at the level of the European Union are of increasing importance as a basic pre-requisite to protect and to improve human health on the continent.18
The EUROHEP.NET Project (2002–2005) is a concerted action granted by DG Research, European Commission; it is a feasibility study for a future European network on surveillance and prevention of vaccine-preventable hepatitis in 28 countries (15 countries of the European Union, the 12 associated states, and Israel).
The aim of the study was to provide evidence of the current systems of data collection for the burden of disease for hepatitis A, in order to propose and to implement European guidelines for a uniform data collection in the field of vaccine-preventable viral hepatitis.
The EUROHEP.NET Project joins surveillance and prevention aspects for hepatitis A and B, respectively, and involves various stakeholders implicated in infectious disease surveillance and control activities (i.e. academia, epidemiologists, Ministries of Health, and the Public Health Institutes).
Within the EUROHEP.NET Project, the Department of Public Health, University of Florence, was assigned the task to analyse the measurement and reporting of burden of disease for hepatitis A and B in all participating countries and give an overall picture of the existing surveillance systems for burden of disease related to vaccine-preventable hepatitis.
In this article, the results concerning hepatitis A are presented.
Two particular aspects had to be analysed: (i) the type of data sources related to the burden of disease and (ii) the numeric data of the burden of disease for hepatitis A during the period 1997–2001. A further objective was to study the feasibility to formulate guidelines in order to enable uniform measurement and reporting of the burden of disease related to hepatitis A.
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Methods |
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At the start of the EUROHEP.NET Project, 28 countries were invited to participate in this feasibility study through their Ministries of Health and/or National Institutes for Public Health.
All the information on the Project and an online survey were available from the EUROHEP.NET website (www.eurohep.net). The survey questions concerned organisation of the surveillance system, case definitions used, burden of disease, epidemiology, vaccination programmes, and strategies for hepatitis A prevention.
Twenty countries agreed to actively collaborate and completed the EUROHEP.NET online survey (2003) for hepatitis A. The countries who accepted to take part to the Project were Austria, Belgium, Bulgaria, Czech Republic, England and Wales, Estonia, Germany, Greece, Hungary, Israel, Italy, Latvia, Lithuania, Luxembourg, Malta, The Netherlands, Poland, Romania, Slovakia, and Slovenia. Norway and Turkey joined the project in May 2004.
We analysed the data related to the burden of disease for hepatitis A obtained through the online EUROHEP.NET survey.
The first analysis was performed with survey results related to the data sources of national surveillance systems on burden of disease supplied by each country correspondent. In particular, an analysis/comparison of the data sources related to hospital admission for acute hepatitis A and the data sources related to mortality due to hepatitis A were made.
The second analysis was carried out on numeric data related to burden of disease in each involved country (total number of hospitalised cases, hospitalisation days, deaths, liver transplants, and proportion of those HAV-related) during the 5 years (1997–2001). The evolution of burden of disease for hepatitis A in all participating countries was also evaluated.
Based on the results of the EUROHEP.NET survey, an overview and comparison among different surveillance systems for burden of disease for hepatitis A was generated.
After analysis of all data, a list with additional questions was also prepared for sending to the participating institutes to have supplementary information and feedback by country correspondents on these topics in order to validate and approve the data. These additional results were included in the EUROHEP.NET database.
Official agreement to publish the data was obtained by signature from all involved country correspondents.17
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Results |
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Generally, almost all countries specified the sources of data regarding burden of disease for hepatitis A (hospital admission and mortality). The data sources were subdivided into three categories with different surveillance system structure: official notification, hospital statistics, and clinical records. In some countries, the data sources were not available. In others, although available, data sources were not specified (table 1).
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In figure 1, the total number of countries with complete, incomplete, and no response to the five survey questions on numeric data of burden of disease for hepatitis A during the 5 years (1997–2001) are shown.
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Although 18 out of 22 countries (82%) have a data source related to hospital admission for acute hepatitis A (table 1), only 15 countries (68%) supplied complete data on hospitalised cases and only 7 (32%) on hospitalisation days.
Nineteen out of 22 countries (86%) have a data source related to mortality due to hepatitis A but only 16 (73%) countries have complete accessible data.
Regarding the total number of liver transplants, only 11 out of 22 (50%) countries have available data on this topic and only three countries (Slovenia, Slovakia, and England/Wales) have data on the proportion of liver transplants due to hepatitis A.
Table 2 shows the total number of hospitalised cases per 100 000 inhabitants and the hospitalisation rate, defined as the number of hospitalised subjects divided by the number of subjects affected with hepatitis A in all countries involved in the EUROHEP.NET Project, and expressed as a percentage. It must be underlined that such rate is an artificial and possibly biased one, since it is calculated on data derived from very different sources (hospital discharge forms and disease notifications), and should therefore be regarded as an useful but not extremely precise index.
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Data show a great variability of hospitalisations for hepatitis A among all the participating countries. The differences in hospitalisation rates are also noteworthy. As a matter of fact, in five countries (Bulgaria, Czech Republic, Hungary, Romania, and Slovakia) hospitalisation is compulsory for each case of hepatitis A. All suspect cases must be admitted to an infectious disease hospital ward: in reality, a minority of cases are treated at home by family doctors. For example, the correspondent from one of these countries reported that 10–20% of cases are missing when computed by the system of compulsory hospitalisation. In addition, an initial suspect hospitalised case might not have been confirmed later. It should be underlined that these data reflect the number of hospital admissions: one patient might have been admitted several times a year with the same diagnosis.
Sometimes (for example in Belgium and Latvia) hospital data are available only at regional level and not collected at the national level or are not timely in some regions.
Many countries used ICD-9 code for notification of cases of hepatitis, which does not allow distinction between hepatitis A and B or between acute and chronic cases.
Some countries (Belgium, Romania, and Israel) explained that reported hospitalisation cases are underestimated.
The reported data of England and Wales refer to a different period of time (financial year, from April to March).
Concerning the total number of hospitalisation days for hepatitis A cases, only few countries have data available on this topic: Austria, Czech Republic, Hungary, Italy, Lithuania, Malta, and Slovakia reported data for the considered period, while England/Wales and Germany have only incomplete data. The mean length of hospitalisation per hepatitis A case is 10 days, with a range of 4–15 days.
Table 3 shows the total number of deaths, mortality per 100 000 inhabitants and case fatality rate (CFR) due to hepatitis A. The results reveal that there are only few deaths due to hepatitis A, confirming the low mortality for hepatitis A, which is in accordance with the WHO figures. In fact, WHO reports a CFR of 0.1% for children (
14 years), 0.3% for young adults (15–39 years) and 2.1% for older persons (
40 years).19
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As for hospitalisation rate, CFR is an artificial index calculated from two very different sources of data and it should be valued with caution.
Concerning the total number of liver transplantations, these data are not available in eight countries (Czech Republic, Greece, Luxembourg, Norway, Poland, Romania, The Netherlands, and Turkey). In addition, in Bulgaria, Latvia, and Lithuania no liver transplants were performed while in Malta the patients requiring such interventions are transferred abroad. In the other 10 countries, the total number of liver transplantations is available for the considered period with an average incidence of transplants of 0.8 per 100 000 inhabitants and a range of 0.1–1.7 among the participating countries. In Belgium and Italy these data are not complete for the 5 years.
Only Slovakia, Slovenia, and England/Wales among countries that perform this kind of surgery answered giving hepatitis A-specific liver transplant data. In England/Wales, only one case in 1998 (0.2%) of liver transplants were reported to be caused by hepatitis A, while no case was reported for the other years. In Slovakia and Slovenia no liver transplants were due to hepatitis A. However, in Slovakia there were only two transplants during 2001 and in Slovenia only 32 liver transplants were performed during the considered period.
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Discussion |
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This concerted action represents a study attempt to give an overview on the surveillance systems for vaccine-preventable hepatitis focused on the larger Europe, which includes not only the original 15 Member States but also the new Member States and associated states to the Union. Although the interpretation of results needs caution for possible biases, nonetheless it represents a first step of knowledge towards standardisation.
Of course, it must not be forgotten that data published in the present report had no further validation except that at country level. A permanent validation and updating of these data is essential as part of the main aim of the project (the feasibility of a future network).
EUROHEP.NET questions covered a broad area, going from epidemiology, burden of disease, vaccination policy, and country correspondents might not always have had direct access to the required data. It could be interesting to integrate the missing data by trying to identify other correspondents with direct access to part of the requested information.
In addition, some countries declared that reported data underestimate the real incidence of disease. Underreporting and differing sensitivities of surveillance systems from various countries is a major issue while comparing surveillance data from different systems. A further development might be an analysis of the amount of underreporting in all countries in order to value the current amount of burden of disease (for example, by using the capture–recapture method).20–24
The EUROHEP.NET survey required data during the 5 years from 1997 until 2001. It would be advisable to gather data on burden of disease up to now in order to confirm the obtained evolution of trend for hepatitis A during the previous 5 years. In addition, with implementation of further data collection it will be possible to evaluate changes in the burden of disease vis-a-vis the changing human health policy measures (for example, introduction of universal vaccination, vaccination for specific risk groups, and so on).
Different data sources for hospital admission and mortality due to HAV are in place in the participating countries but it is possible that the same data source has different names among involved countries or the same name represents different data sources.
Not all countries answered all questions on numeric data of burden of disease for hepatitis A: in some countries the data on total number of hospital admissions and deaths due to hepatitis A are not available. Sometimes the available data are not immediately accessible or complete.
Although many countries are able to measure and report the total number of deaths and hospital admission, data on days of hospitalisation, total number of liver transplants, and the proportion due to hepatitis A, B, and C often are not included in the current surveillance systems of burden of disease.
In addition, in some countries data on hospital admission are gathered only for remuneration reasons, not for epidemiological purposes. Sometimes only data from extemporary studies on hospitalisation are available, without a routine registration system.
In a number of countries data are collected regionally and there is no centralised national data collection or their aggregation at the central level is not timely.
Blanks or missing data in the answers to the EUROHEP.NET survey, unless otherwise specified, can either be due to not available/traceable information in the country or to non-availability of such information to the country correspondent at the time of the survey. In the latter case, this does not necessarily mean that the information does not exist.
There is not a unique adoption of ICD-10 code to report the diagnosis of hepatitis for hospital admission or death. The previous ICD-9, still used in many countries, makes no distinction between hepatitis A and B or between acute and chronic cases. ICD-10 was endorsed by the Forty-third World Health Assembly in May 1990 and came into use in WHO Member States since 1994.25 Therefore, the results of the EUROHEP.NET Project highlight that many countries have not yet adopted this standard several years later.26
This study is the first step to propose and implement guidelines for a uniform data collection in order to make plans for a future network on surveillance and prevention of vaccine-preventable viral hepatitis on the larger Europe. However, the overall picture highlights that surveillance data on the burden of disease are not collected in a standardised way. All countries have surveillance systems which allow to determine the burden of disease of vaccine-preventable hepatitis, but a wide diversity exists among them due to different local situations. Sometimes the data sources are present, but data are not immediately available. In addition, discrepancies could exist between the officially recommended procedures and the actually applied criteria in a given country. Therefore, identification of possible hurdles towards harmonisation of the surveillance systems and introduction of standardisation at the European Union level (respecting the current practices in the different countries as much as possible) is a primary need, especially for those data that should be collected in all countries. In particular, all countries should make an effort to systematically collect burden of disease data on hospital admission for hepatitis A, mortality, and liver transplantations according to ICD-10. If possible, the reports with these data should be electronically linked to existing surveillance databases.
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Acknowledgments |
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The authors thank the expert panellists for their invaluable contribution: Austria: J. P. Klein, C. Hain; Belgium: R. Vranckx, L. De Cock; Bulgaria: M. Kojouharova, A. Kurchatova; Czech Republic: B. Kriz; England/Wales: N. Crowcroft; Estonia: N. Kerbo; Germany: K. Alpers, D. Radun; Greece: C. Psichogiou, A. Roumeliotou; Hungary: A. Csohán; Israel: R. Dagan, E. Anis; Italy: L. Vellucci, M. Pompa, T. Stroffolini, S. Iannazzo, A. Mariano; Latvia: I. Jansone, E. Pujate; Lithuania: V. Bakasenas; Luxembourg: P. Huberty-Krau; Malta: C. Gauci, M. Micallef; Norway: H. Blystad; Poland: W. Magdzik, A. Zielinski; Romania: A. Pistol, A. Rafila; Slovakia: Z. Kristufkova; Slovenia: A. Kraigher, L. Pahor; The Netherlands: Y. Van Duynhoven; Turkey: E. Usta, MA. Torunoglu.
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Footnotes |
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*EUROHEP.NET Team: P. Van Damme, A. Vorsters, K. Van Herck and E. Leuridan (Centre for the Evaluation of Vaccination, WHO Collaborating Centre for Prevention and Control of Viral Hepatitis, Department of Epidemiology and Community Medicine, University of Antwerp, Belgium); M. Kojouharova (National Centre for Infectious and Parasitic Diseases, Sofia, Bulgaria); R. Dagan (Pediatric Infectious Diseases Unit, Soroka University Medical Centre, Beer Sheva, Israel); P. Bonanni, S. Boccalini and A. Bechini (Department of Public Health, University of Florence, Italy); J. Hallauer (Universitätsklinikum Charité, Berlin, Germany); W. Usonis (Vilnius University Centre of Paediatrics, Lithuania); W. Magdzik, A. Zielinski and M. Czerwinski (Department of Epidemiology, National Institute of Hygiene, Warsaw, Poland).
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