None of the surveys in the meta-analysis included Puerto Rico in their sampling frames. Because Puerto Rico has a considerable number of HIV diagnoses reported each year and approximately 40% are among PWID [21], we derived a method to calculate HIV rates among PWID in Puerto Rico. A report by Perez and colleagues [22] from a household survey conducted during 2005–2008 indicated that 1.5% of adults aged 21–64 years in Puerto Rico had ever injected drugs (no standard error reported). To calculate a rate, we used the 1.5% population proportion of PWID in Puerto Rico, Puerto Rico population totals from census data [16], and the estimated number of PWID living with diagnosed HIV infection in Puerto Rico in 2010 from CDC's HIV case surveillance data [5]. (Table S1).
