By the Numbers
While HCV prevalence is down, the rate of morbidity may be going up
by Larry Buhl
New data on the prevalence of hepatitis C virus (HCV) in the U.S. shows that, with a “silent epidemic,” it’s hard to get accurate numbers. A disease that often has no symptoms, and that hits populations less likely to get tested hardest, makes data gathering on HCV prevalence and death challenging.
But even with the difficulties in reporting, new data suggest that the prevalence of HCV infections in the U.S. is decreasing, while morbidity among those with HCV may be increasing and under-reported.
Researchers from a new National Health and Nutrition Examination Survey (NHANES) concluded that an estimated 2.7 million people in the U.S. have chronic hepatitis C, substantially lower than the commonly used figure of 3.2 million, a number that was determined by NHANES more than ten years ago. NHANES is a periodic national survey that looks at a representative sample of U.S. households.
The results of the NHANES survey were published in the March 4 edition of Annals of Internal Medicine.
Maxine Denniston, Scott Holmberg, and colleagues from the Centers for Disease Control and Prevention (CDC) reported the latest hepatitis C data from 5,000 NHANES participants surveyed between 2003 and 2010. Their data did not include groups such as active duty military, prisoners, homeless people, or people living in institutions or care facilities. Prisoners and homeless people are known to be at much higher risk for HCV infection.
“This analysis estimated that approximately 2.7 million U.S. residents in the population sampled by NHANES have chronic HCV infection, about 500,000 fewer than estimated in a similar analysis between 1999 and 2002,” the researchers concluded.
The researchers did not speculate on the reasons for the decline in the hepatitis C infection rate. However, Ruth Jiles, Epidemiologist in the Division of Viral Hepatitis at the CDC, tells A&U that “because of the increased number of deaths and hospitalizations for individuals with hepatitis C, the decline may reflect an increase in the number of deaths among those with the disease.”
There are some statistics to back up the rising death number theory.
A CDC study published in the February 12, 2012, issue of the Annals of Internal Medicine analyzed a decade of death records and found an increase in death rates from hepatitis C. It also reported that three-fourths of the hepatitis deaths occurred in the middle-aged, people forty-five to sixty-four. “Mortality will continue to grow for the next 10 to 15 years at least unless we do something different to find and treat the silent sufferers,” Dr. John Ward, hepatitis chief at the CDC told the San Francisco Chronicle upon release of that study.
HCV deaths under-reported?
Not only is the number of HCV-related deaths likely rising, that number may be far greater than anyone thought, according to a new study.
A report published in the February 12 edition of Clinical Infectious Diseases, concludes that hepatitis C is under-documented on death certificates of people who die with the disease. Reena Mahajan from the CDC and colleagues looked at disease-specific, liver-related, and non-liver-related mortality among people with HCV in the observational Chronic Hepatitis Cohort Study (CHeCS) at four U.S. healthcare systems. They compared this to Multiple Cause of Death (MCOD) data from 12 million death certificates recorded in 2006–2010.
Mahajan and colleagues found that only about twenty percent of people with HCV-related chronic liver disease had this listed as a cause of death, even though a majority had evidence of moderate or advanced liver fibrosis.
HCV infection is greatly under-documented on death certificates, the authors summarized. “The 16,622 persons with HCV listed in 2010 may represent only one-fifth of about 80,000 HCV-infected persons dying that year, at least two-thirds of whom (53,000 patients) would have pre-mortem indications of chronic liver disease.
“Data from this study suggests a much greater role of HCV on mortality in the United States than has been previously understood based on analyses of death certificate data,” they continued in their discussion. These data “contradict prevalent views that, perhaps because of its long incubation period (30 years), HCV infection is an indolent infection that is not of urgent concern.”
Among the 156 HCV-positive CHeCS patients who had liver transplants, only forty-six (twenty-nine percent) had HCV noted on their death certificate.
“Even if we exclude other diseases associated with HCV infection such as diabetes and non-Hodgkin lymphoma, it appears that most are dying not just with HCV but possibly from HCV,” the authors wrote.
Jiles tells A&U that the new data on HCV prevalence and HCV-related deaths suggest that testing is crucial for a personal and public health perspective. “New therapies only work if people receive them. The potential of current and other advances depends on our ability to get more people screened and into care.”
Larry Buhl is a radio news reporter, screenwriter, and novelist living in Los Angeles. His young adult novel, The Genius of Little Things, debuted last year.