For national estimates of the prevalence of HCV infection, CDC relies on data from NHANES, which includes both an interview and HCV antibody testing of the respondent, allowing for calculation of disease rates by identification of persons reporting lifetime injection drug use among those who are anti-HCV positive. We analyzed NHANES data from 2003–2010 for persons aged 40–65 years. This age range captures a majority of those who may have reported injection drug use and roughly corresponds to the age group for which CDC recommends one-time HCV testing without prior ascertainment of HCV infection risk [11]. To calculate the denominator for the rate, the estimate for the population proportion of PWID in the age group 50–64 years was applied to 2011 census data for persons aged 40–65 years (Table S1).
