Hepatitis C: universal or selective screening?

The major aim in screening for any disorder is the prevention of future ill health and/or the treatment of asymptomatic clinical disease. Guidelines have been produced with regard to physician initiated screening for medical conditions; most importantly, the condition should be an important health problem, there should be an accepted form of treatment, a suitable and acceptable test, and facilities for its diagnosis; the natural history should be well understood and a latent or early symptomatic phase is necessary to allow time for any possible intervention. At first glance these guidelines appear to be admirably fulfilled for infection with hepatitis C virus (HCV) and, without much discussion, widespread screening for this disorder has been initiated particularly among those infected via injecting drug use (IDU). Without a doubt HCV is an important health problem; 80% of those infected develop chronic liver disease and it is a major cause of chronic liver disease which in the United States is only slightly less common than that caused by chronic alcoholism. 3 In the United Kingdom around 3000 blood donors have been confirmed as HCV antibody positive, around 5000 haemophiliacs are estimated to have been infected before screening for HCV was introduced, and around 100 000 individuals are estimated to have been infected via IDU. There is an acceptable treatment, interferon alfa, and relatively simple blood tests for the diagnosis or monitoring of treatment for HCV infection, although a more invasive procedure in the form of a liver biopsy may also be required. There is a very definite latent or early symptomatic phase with a possible median time to serious disease (cirrhosis) of maybe 30 years or longer. Despite these apparent advantages for screening there are some technical problems, particularly that some patients may be missed by current tests. We now know that loss of HCV antibody occurs at a rate of around 0.6/100 patient years but that this does not necessarily imply loss of virus or infectivity. Thus, for every 1000 infected patients screened six will have a negative test after 1 year of HCV infection, 60 after 10 years, 120 after 20 years, and 180 after 30 years of infection, an error rate of around 1–2%. For individuals with a definite risk activity, like IDU, this can be overcome by testing earlier specimens or arranging for a PCR test if early specimens are not available. Thus, as always if undertaking screening, it is important to be aware of the implications and limitations of a negative test as much as a positive test. Unlike HIV, there has been no major debate on the wisdom or not of widespread screening for HCV in at risk populations. In 1995 under the aegis of the Royal College of Physicians Edinburgh, the medical director of the Scottish Blood Transfusion Service met with a group of interested clinicians to discuss the problem of screening for individuals possibly infected with HCV via blood transfusions. Their conclusion concerning anyone possibly at risk of HCV from a blood product was: “Person identified as being potentially HCV positive must be told . . . there is a duty to provide care and support for these patients to the highest clinical standards.” Was this conclusion reasonable, can it be applied to all other individuals at risk of HCV infection, or was it simply related to the possibility of legal action? Since it may take 30 years to develop clinical disease or illness from HCV who is the beneficiary from widespread screening for HCV—the patient or the community? Are we trying to prevent spread of HCV infection, reduce progression to disease, or reduce legal liability? In the case of HIV, which is readily transmissible via both IDU and sexual intercourse and is a major threat to the non-drug using population, considerable eVorts were made to set up counselling services and treatment facilities. By comparison, screening for HCV, which is rapidly spread via injecting drug practices but rather ineYciently spread via sexual intercourse, has received little attention and little in the way of additional resources. The only therapy of proved benefit for chronic HCV hepatitis is interferon alfa, which is eVective in only around 20% of patients and unfortunately has a number of exclusions and diYcult side eVects. In Edinburgh, where additional funds for the treatment of HCV have not been allocated, individuals are not eligible for shared care interferon therapy with general practitioners if the treatment is likely to be ineVective or if there is an increased risk of an adverse event. Individuals currently excluded from the shared care protocol are those with the following problems—obesity (a body mass index >35); an immunocompromised state; in the presence of liver failure or early cirrhosis, pre-existing hepatocellular carcinoma; other causes for chronic liver disease such as alcohol, autoimmune hepatitis, significant comorbidity such as cardiac or renal disease; poor compliance with injection therapy or follow up; specific contraindications to interferon therapy such as depression, epilepsy, psoriasis, poor central neurological function; and of course any previous allergy to interferon. If these exclusion criteria for treatment are to be applied, is it then ethical to screen an individual at risk for HCV in the presence of a pre-existing exclusion criterion for treatment? Similarly, if the facilities for diagnosis and treatment of HCV were not available, either as a result of a lack of expertise or lack of funds Sex Transm Inf 1998;74:374–375 374