An estimated 813,000 people with diagnosed hepatitis C in the US have undergone liver disease staging and meet the 'highest' or 'high' priority criteria for immediate treatment, according to an analysis presented at the American Association for the Study of Liver Diseases (AASLD) Liver Meeting last month in Boston. The number would be even higher if taking into account undiagnosed individuals and prisoners and others excluded from household surveys.
Over years or decades chronic hepatitis C virus (HCV) infection can progress to serious liver disease including cirrhosis, hepatocellular carcinoma and liver failure.
Successful treatment can slow or halt liver disease progression, and may even allow for some degree of recovery.
When the standard of care was interferon-based therapy -- which lasted up to a year, caused difficult side-effects and cured only about half of patients - treatment was recommended only for people with moderate or worse liver damage (Metavir stage F2 or higher).
Now that highly effective and well-tolerated direct-acting antiviral regimens are available, some experts are calling for treatment for everyone living with hepatitis C. But due to the drugs' high cost, many national health systems and private insurers are limiting treatment to the sickest patients.
This past August, experts from the American Association for the Study of Liver Diseases (AASLD), the Infectious Diseases Society of America and the International Antiviral Society-USA released guidelines about who should be treated for hepatitis C and when (available at www.hcvguidelines.org).
While noting that everyone with chronic hepatitis C could potentially benefit from treatment, they recommended that when resources are limited the 'highest priority' should be given to patients with advanced fibrosis (stage F3), those with compensated cirrhosis (stage F4) and liver transplant recipients. 'High priority' should be given to people with moderate fibrosis (stage F2) and those with less advanced fibrosis who have comorbidities or are at risk for complications.
Fujie Xu and colleagues from the US Centers for Disease Control and Prevention (CDC) and colleagues aimed to estimate the number of people living with hepatitis C in the US, and the number who have been diagnosed, who fall into the 'highest' or 'high' priority categories.
The researchers used data from the National Health and Nutrition Examination Survey (NHANES) conducted in 2003-2010 to estimate the number of people living with hepatitis C in the US, whether diagnosed or not. This is a nationally representative household sample but does not include certain groups with higher HCV prevalence such as incarcerated individuals and members of the military. Among the estimated 2.7 million non-institutionalised civilians with chronic hepatitis C, they assumed that half, or 1.35 million people, have been diagnosed.
They also used data from the Chronic Hepatitis Cohort Study (CHeCS), an observational study of hepatitis C patients receiving care at integrated healthcare systems in four cities, to estimate the distribution by fibrosis stage of patients who have been diagnosed and staged by liver biopsy or FIB-4 score. FIB-4 is a non-invasive index that incorporates age, alanine and aspartate aminotransferase (ALT and AST) levels and platelet count, and can therefore be calculated from common lab test results. A FIB-4 cut-off of 1.6 indicates Metavir stage F2 while a cut-off of 2.5 indicates stage F3.
Comorbidities and complications were identified using laboratory tests and ICD-9 diagnostic codes from medical records.
The researchers estimated that 19% of all people living with hepatitis C, or 513,000 individuals, had stage F3 or higher fibrosis. Another 0.7%, or 18,900 people, had a lower fibrosis stage with kidney disease. Taken together, they estimated that 532,000 people would be classified as 'highest' priority.
They further estimated that 15% of people with hepatitis C, or 405,000 individuals, had stage F2 fibrosis, while another 4%, or 108,000 people, had less extensive fibrosis with comorbidities. Together, an estimated 513,000 people would be classified as 'high' priority.
Adding these two groups together, a total of 1.045 million people living with hepatitis C were estimated to meet the criteria for 'highest' or 'high' priority for treatment.
Using CHeCS data, the investigators estimated that 1.27 million people have been diagnosed with HCV infection and had either biopsy results (22%) or FIB-4 scores (72%) available.
Within this group, they estimated that 33%, or 419,000 people, had stage F3 or higher fibrosis and 3%, or 38,000 people, had lower fibrosis stages with kidney disease, for a total of 457,000 individuals considered to be 'highest' priority.
Further, they estimated that 22%, or 280,000 people, had stage F2 fibrosis and 6%, or 76,000, had lower stages with chronic comorbid conditions, for a total of 356,000 individuals considered to be 'high' priority.
"About 1 million non-institutionalized person with HCV infection in the United States met the 'highest' priority or 'high' priority criteria for immediate treatment," the CDC team summarised. "Of these an estimated 813,000 had been diagnosed and staged by biopsy or had received the clinical workup for the calculation of FIB-4 score."
"For the majority of patients whose HCV infection has been diagnosed, access to HCV treatment immediately or soon is important due to their stage of liver fibrosis or comorbidities," they concluded, adding that high treatment costs and lack of access to a treating clinician are among the potential barriers to receiving hepatitis C treatment.
A related study presented at the conference found substantial liver disease progression among hepatitis C patients in CHeCS who meet liver disease criteria conferring a 'highest' or 'high' recommendation for treatment.
Xu F et al. Estimating the number of patients with chronic hepatitis C infection according to liver fibrosis stage in the United States. American Association for the Study of Liver Diseases (AASLD) Liver Meeting, Boston, abstract 1757, 2014