Interferon alfa (pegylated and non-pegylated) and ribavirin for the treatment of chronic hepatitis C

The total budgetary impact of combination therapy depends on a number of factors: prevalence, proportion of people diagnosed, proportion of the people diagnosed who attend for assessment, and the proportion considered suitable for treatment, as well as the proportions who actually take up therapy and complete it. It also depends on whether peginterferon alfa combination treatment is being compared with interferon alfa combination therapy, peginterferon alfa or interferon alfa monotherapy, or no treatment.

Currently, only about 2,000 people in England and Wales each year are being treated for HCV infection with some form of interferon or peginterferon alfa therapy. On the basis that all these people will eventually receive peginterferon alfa combination therapy, that the numbers being treated do not change with time, and that peginterferon alfa combination therapy costs about £3,200 more per patient than interferon alfa combination therapy, the additional drug expenditure would be up to £6.4 million per year. However, it is likely first, that the number of people able to benefit from treatment (injecting drug users and people who have had an alcohol problem) will be increased as a consequence of this guidance, and second, that the number of people seeking treatment will increase as education about the condition increases and as people become aware of improvements in treatment. This would significantly increase drug expenditure.

Testing people with G1+ infection at 12 weeks and ending treatment for those who are not responding to therapy would cut the additional costs by about 16%, or about £1 million.

There will also be a re-treatment cost for non-responders to previous therapy. The numbers of people involved are not known with any degree of certainty. The following assumptions have been made:

• 1,000 people have not had an SVR to monotherapy and have not subsequently been treated with a combination therapy

• 250 are still alive and would wish to undertake peginterferon alfa combination therapy

• 60% are G1+ and 40% are G2 or G3

• half of the people with G1+ respond after 12 weeks and are treated for 48 weeks at a cost of £12,000 each

• the other half of the people with G1+ are treated for 16 weeks at a cost of £4,000 each

• the people with G2 or G3 are treated for 24 weeks at a cost of £6,000 each

• the number of people who have been treated with previous interferon combination therapy but who have either not responded or have relapsed is 2,000, of whom 75% (1,500) are G1+ and 25% (500) are G2 or G3

• 1,000 of the G1+ and 400 of the G2 and G3 seek re-treatment

• 25% of the G1+ group respond after 12 weeks and are treated for 48 weeks at a cost of £12,000 each; the 75% that does not respond are treated for 16 weeks

• the G2 or G3 group is treated for 24 weeks at a cost of £6,000 each.

The drug cost, compared with no interferon treatment, would be approximately £1.8 million for people who have had previous monotherapy treatment and a further £8.4 million for people who have had previous combination therapy treatment. This is likely to be spread over about 2 years, equating to £5.1 million per year. The total increased drug cost for the next 2 years would therefore be about £10.5 million per year. Should people seeking re-treatment delay further treatment, the costs per year would be lower than £10.5 million per year, but would be spread over a longer time period.

This estimation procedure ignores other costs, such as the cost of testing for genotype and viral load, but also ignores the additional potential treatment offsets down the line.