An update to a large national health survey finds that the total number of people infected with Hepatitis C virus has not changed substantially between 1994 and 2002.
However, the most frequent age bracket of those infected has shifted from 30 to 39 in the earlier study to 40 to 49 in the current study.
Most infected people engaged in intravenous drug use in their youth.
These patients are now entering the age when the consequences of Hepatitis C infections, such as cirrhosis, liver cancer and kidney disease, begin.
Dr Gregory Armstrong and colleagues conducted a nationally representative household survey of a US civilian, noninstitutionalized population.
The team included 15,079 participants in the National Health and Nutrition Examination Survey between 1999 and 2002.
|48% of anti-Hep C-positive patients reported a history of injecting drugs|
|Annals of Internal Medicine|
All participants provided medical histories, and those who were 20 to 59 years of age provided histories of drug use and sexual practices.
Participants were tested for antibodies to Hepatitis C and Hepatitis C virus RNA, and their serum alanine aminotransferase levels were measured.
The investigative team found that the prevalence of anti-Hepatitis C in the US was almost 2%.
This equates to an estimated 4 million anti-Hepatitis C-positive persons nationwide.
The team noted that about 1%, or 3 million persons had chronic Hepatitis C infection.
Peak prevalence of anti-Hepatitis C was observed among persons 40 to 49 years of age.
A total of 48% of anti-Hepatitis C-positive persons between 20 and 59 years of age reported a history of injection drug use.
This is the strongest risk factor for Hepatitis C infection.
Of all persons reporting such a history, 83% had not used injection drugs for at least 1 year before the survey.
The team observed that other significant risk factors included 20 or more lifetime sex partners and blood transfusion before 1992.
Abnormal serum alanine aminotransferase levels were found in 59% of Hepatitis C RNA-positive persons.
A combination of these 3 characteristics identified 85% of Hepatitis C RNA-positive participants between 20 and 59 years of age.
Dr Armstrong's team commented, “Many Americans are infected with Hepatitis C.”
“Most were born between 1945 and 1964 and can be identified with current screening criteria.”
“History of injection drug use is the strongest risk factor for infection.”
Dr Jules Dienstag, editorial writer of Annals of Internal Medicine, adds, “The ‘curious distribution' of Hepatits C infection probably reflects the aging of the same cohort with HCV infection that was identified during the 1988-1994 survey”.
”These people, now in their 40s and 50s, acquired their infections primarily through injection drug use that began in the 1960s and peaked in the 1980s, a time of widespread experimentation with substances of abuse.”
"This cohort has lived with unrecognized Hepatitis C infection for several decades.”
“However, as they age, they are more likely to seek regular medical care and apply for life insurance, unearthing their Hepatitis C infection.”