Heroin and Xylazine Combined: A Contributing Factor to HIV Risk Behaviors in Puerto Rican Drug Users

Background and Purpose: According to the US Center for Disease Control (2012), incidence of HIV in Puerto Rico was 28.6 per 100,000 persons, while the U.S. National rate was 19.1. In recent years Puerto Rican injection drug users (IDUs) reported combining xylazine (street name horse anesthesia, a veterinary sedative) with heroin.  Research shows that xylazine contributes to more severe symptoms of dependence and withdrawal if the drug is not available. Given the growing use of this drug combination, this study explored the association between the use of heroin vs. heroin+xylazine and engagement in HIV risk behaviors among Puerto Rican IDUs living on the island.

Methods: Data from 451 Puerto Rican drug users was gathered through survey interviews in Spanish between 2007- 2013, using a cross-sectional survey design. Interviewers approached individuals in areas of San Juan, Rio Piedras and Ponce where drug users were known to gather. Study eligibility was verified by screening their age (18 or older) and opiate use. Participants received a code based on date of birth and mother’s name to prevent the same respondent from taking the survey multiple times. The study included questions from the Substance Abuse Mental Health Service Administration, Government Performance and Results Act questionnaire and a revised National Institute of Drug Abuse validated Addiction Risk Behavior Assessment battery.  The questionnaire was translated to Spanish, back-translated and adapted for Puerto Ricans. Bivariate analyses were conducted to explore the association between heroin and xylazine use and HIV risk behaviors (sharing drug-paraphernalia, being injected by others, injecting others, unprotected sex).  Logistic regression analysis compared the risks associated with heroin use without xylazine vs. heroin+xylazine on HIV risk behaviors, controlling for demographic characteristics, housing status, substance use history and mental health symptoms.

Results: 79% of IDUs were male; 54% did not have a high school diploma, 28% graduated high school and 18% had some college;  81% were homeless or in temporary housing.  Incidence of ever having injected heroin and xylazine was high (73.4%), while 26.6% reported having used heroin without xylazine. Respondents were more likely to inject drugs more than 5x/day if they used heroin and xylazine (OR=9.571, CI 4.72 –19.39), compared to those who injected heroin only (OR = 2.40, CI 1.13 – 5.07).  Heroin+ xylazine users were also significantly more likely to have shared needles or works (OR = 2.73, CI 1.34 – 5.57) compared to heroin users only (OR=.88, CI .42 – 1.82). They were also significantly more likely to have injected others (OR = 5.79, CI 2.59 – 12.98) and to have been injected by others (OR=5.27, CI 2.36 – 11.77). Interestingly, heroin+xylazine use was not associated with having had unprotected sex in the past 30 days.

Conclusions and Implications: Resources and policies for HIV prevention efforts in Puerto Rico must address the use of heroin+xylazine combined, its health consequences and its association with HIV risk behaviors. Furthermore, research of migratory patterns of Puerto Ricans IDUs traveling to and from the US mainland may suggest risks for heroin+xylazine use across these geographical borders.