Diagnosing Hepatitis C With Improved Screening Strategies
Author:
Raymond T. Chung
Massachusetts General Hospital
Citation:
Chung RT. Diagnosing hepatitis C with improved screening strategies [published online March 6, 2019]. Infectious Diseases Consultant.
The diagnosis of hepatitis C virus (HCV) is and always has been a fairly straightforward proposition where patients generally come to attention through 1 of 2 ways. The first and most likely way is through the identification of abnormal liver function tests on an annual physical examination. The second is through risk factor-based screening.
Annual Physical Examination
Patients found to have elevated enzymes should be administered an evaluation that includes an antibody test for HCV. A positive antibody test for HCV should then prompt the health care provider to administer a confirmatory HCV RNA test, which confirms or denies the presence of active viremia.
If the RNA test is positive, the patient can be considered—with few exceptions—chronically HCV infected and is thereby considered a possible candidate for antiviral therapy.
Individuals who test positive for antibody to HCV but negative for HCV RNA are most likely to have had prior infection with HCV that was spontaneously cleared by the immune system or harbor a false positive antibody to HCV. And much of whether or not that is a false positive really depends on the prior probability of that patient having exposure to HCV—for example, do they have risk factors for HCV?
Risk Factor-Based Screening
If a history of injection drug use at any time or receipt of blood transfusions before 1992 is elicited in a history, then those patients should be evaluated for HCV on the premise that these are the two most important risk factors for infection.
However, this route of diagnosis has been historically very inefficient, largely because health care providers do not ask about those histories and risk factors, and most patients do not volunteer it. Between a reluctance to ask and a reluctance to answer, there has been limited yield on the risk factor screening front.
And so it is not surprising that when it came to population screening for HCV, where it was felt that most of the HCV epidemic or burden was not being uncovered through routine office examinations, that using a risk-factor-based approach to screening was judged to be inadequate.
In turn, a third approach was required to improve the yield of chronically infected patients.
Improving Screening Strategies
In 2012, the Centers for Disease Control and Prevention recommended a much more blanket screening approach: a one-time screen for adults born between 1945 and 1965.
It was projected that up to 80% of the HCV epidemic resided in the baby boomer generation, and so the yield from the new screening approach was expected to be higher.
The key development that helped spur this significant change in screening strategy was the advance in therapeutics to the point where we now have highly effective, all-oral regimens that are extremely well-tolerated by patients, producing high rates of cure.
This was a far cry and great improvement over the prior interferon-based treatments for which patients had to endure numerous, often disabling side effects. As a result, therapeutic nihilism in many ways promoted diagnostic nihilism. With improvements in treatments, there was clearly a very strong impetus to improve diagnostic yield.
Now, with cure rates with all-oral regimens approaching 100% for all forms of HCV, coupled with more mass screening, we can now hope that the great scientific advances in the management of HCV could be parlayed into many more patients diagnosed and into many more cures as a result.
Raymond T. Chung, MD, is the vice chief of the Gastrointestinal Division, director of Hepatology, and medical director of the Liver Transplant Program at Massachusetts General Hospital in Boston.