For the denominators, we used the estimated number of lifetime PWID. Denominators were calculated by multiplying census data by the lifetime PWID population proportion derived from the meta-analysis. Our choice to use the estimate based on lifetime injection drug use behavior for calculating rates best corresponds to the HIV surveillance definition, which is injection drug use since 1977 [5]. We used 2011 and 2010 census data, respectively, to determine the number of PWID for the HIV diagnosis rates and rates of living with diagnosed HIV infection (Table S1).
