Compared to the overall population of those living with hepatitis C virus (HCV), injection drug users (IDUs) tend to be much younger when they develop serious liver damage from HCV, show new findings published in the International Journal of Drug Policy and reported by New York University, where the comparative analysis took place.

For the study, researchers at the NYU Center for Drug Use and HIV Research reviewed 21 studies examining more than 8,500 IDUs around the world. Researchers specifically looked at four major HCV-related outcomes among this population—fibrosis progression rates, the incidence of both compensated and decompensated cirrhosis, and rates of hepatocellular carcinoma (HCC, the most common form of liver cancer) over the course of a long-term infection with the virus.

Among these injection drug users, researchers found that the mean age of hep C transmission was 21 years old. Then, based on their analysis of disease progression, researchers found that IDUs, on average, will develop liver fibrosis within 26 to 38 years of getting HCV, and are likely to develop cirrhosis within 34 to 46 years of diagnosis.

Researchers noted that these progression rates, coupled with the young average age of initial diagnosis, means that IDUs are likely to develop HCV-related complications far earlier in life than the rest of the HCV population—with folks often falling seriously ill by mid-to-late-adulthood.

NYU scientists said they hoped that by providing a better understanding of HCV progression among IDUs, they would help expand access to earlier testing, diagnosis and treatment in this group.

In most high-income countries, injection drug use is the primary mode of hep C transmission. Worldwide, an estimated 50 to 80 percent of people who inject drugs are chronically infected with HCV; however, fewer than 5 percent so far have received treatment.