The hepatitis B virus (HBV) is a blood-borne and sexually-transmitted virus. Worldwide, approximately 350–400 million people have chronic hepatitis B infection, with prevalence estimates ranging from below 2% in low- endemic countries, to greater than 8% in highly-endemic countries. In Australia, between 0.5 and 2.0% of the population are chronically infected, approximately half of whom are immigrants born in high-endemic countries.

The majority of people with chronic hepatitis B infection, defined as hepatitis B infection lasting 6 months or more, have inactive disease. Around one-fifth to one-quarter has active disease, i.e., chronic hepatitis B. These individuals are particularly at risk of developing life-threatening complications including cirrhosis and liver cancer. Most of the burden of disease and the associated economic costs are associated with these serious sequelae. Around seven thousand disability adjusted life years (DALYs) are lost each year due to hepatitis B in Australia, most of which is due to premature death.

There are three main strategies for dealing with HBV infection in a population – screening, vaccination and treatment. There are currently no screening programs for hepatitis B in Australia. An infant HBV vaccination and adolescent catch-up

program has been in place for over a decade. HBV drug therapy, used to suppress viral replication and liver disease progression, is currently only received by a small proportion of those eligible for treatment. In addition, a small number of liver transplants are performed each year in those with advanced liver disease.

Although Australia has adopted universal hepatitis B vaccination for infants, there are many people already infected for whom vaccination offers no benefit. This, coupled with immigration patterns, the fact that the infected pool of individuals is now ageing and that only a small number of people receive HBV drug therapy, means the long-term sequelae of HBV infection can be expected to become increasingly evident over the forecast period.

This report provides a comprehensive review of the epidemiology and economics of HBV infection in Australia, and projects the mortality, morbidity and direct economic costs likely to arise from HBV infection over the next decade. It also investigates the cost-effectiveness of increasing the number of people who receive drug therapy for chronic hepatitis B, and considers the economic justification for investing in a national strategy for hepatitis B.

Markov mathematical simulations are used to model the current and projected burden of chronic hepatitis B infection in Australia from 2008 to 2017. Three scenarios are considered:

• Scenario I is a natural history scenario in which patients receive all medical care excluding drug therapy to treat chronic HBV infection;

• Scenario II reflects current treatment and management practices, where a small proportion of patients receive drug therapy; and

• Scenario III involves a nationally coordinated approach, which increases the proportion of people infected with HBV being treated.

For each of these scenarios, projections are made on the mortality and morbidity associated with hepatitis B and the direct health costs, using data largely derived from published sources.

• Based on the current estimated incidence rate of chronic HBV infection of 55 per 100,000 population, there will be a substantial increase in the number of people living with chronic hepatitis B infection in Australia in the next decade. It is estimated that, at the beginning of 2008, there were about 187,000 people living with chronic hepatitis B infection. Under current management and treatment practices (Scenario II), this will increase to around 276,000 (a 48% increase). Of these 276,000, about 182,000 (66%) will have inactive disease while the remaining 94,000 (34%) will have active disease (i.e. chronic hepatitis B).

• A large increase in the number of cases of liver cancer and deaths attributable to hepatitis B over the same period is also predicted. At the end of 2008, it is estimated that there were about 500 people living with HBV-related liver cancer. A more than three-fold increase in this number to 1,600 is projected by the end of 2017. The number of deaths attributable to hepatitis B each year will increase from 450 in 2008 to 1,550 in 2017.

• The direct cost of management and treatment of HBV infection under current practices is projected to increase from $171.8 million in 2008 to $307.9 million in 2017 (2008 prices) — an 80% increase. Total direct costs over the ten years are projected to be $2,377.5 million.

• Although several drugs for treating HBV infection (anti-virals and interferon) are currently listed on the Pharmaceutical Benefits Scheme (PBS),

• it is estimated that only 13% of people with chronic hepatitis B receive such therapy to treat their infection. There is considerable scope to increase the uptake of drug therapy by those who qualify for it.

• Under Scenario III — the enhanced management and treatment scenario — the proportion of people with chronic hepatitis B receiving drug therapy would increase from 13% to 41%. This is projected to result in:

• 1,020 people living with HBV-related liver cancer in 2017 compared with 1,600 people in that year if current management and treatment practices continue;

• 950 HBV-related deaths in 2017 compared with 1,550 in that year if current management and treatment practices continue; and

• an increase of $498.5 million in the 10-year total direct costs, from $2,377.5 million to $2,876.0 million.

• The incremental cost per life-year saved under Scenario III compared with Scenario II is $29,575 (discounted).

• If the maximum willingness-to-pay for a life-year saved is $57,000 then an investment of $365 million over 10 years, over and above the additional costs of treatment, to achieve the outcomes associated with Scenario III would be economically justified.

According to the report, under current levels of medical management and treatment:

• The number of people living with chronic hepatitis B infection will increase from 187,000 to 276,000

• The number of deaths attributable to chronic hepatitis B each year will increase from 450 in 2008 to 1,550 in 2017

• There will be a three-fold increase in the number of people living with liver cancer directly caused by hepatitis B

In 2017, there will be three times as many cases of HBV-related liver cancer than in 2008, and a marked increase in the number of

deaths attributable to HBV, under current treatment patterns. Concomitantly, increasingly heavy demands on liver clinics nationwide can be expected. While the costs of managing and treating HBV infection can therefore also be expected to increase, this report argues that this investment is economically justified, given the cost-effectiveness of drug therapy for chronic hepatitis B.

The results presented in this report underscore the importance of the National Hepatitis B Strategy currently being developed for Australia, and suggest that the development of this Strategy should be regarded as matter of priority.