Hepatitis C and syringe sharing: A systematic review (USA, 1988–2019) and cross-sectional descriptions (Hawaiʻi, 2019) of risk behaviors among people who inject drugs

Abstract

The multiperson use, or sharing, of needles and drug injection equipment among people who inject drugs (PWID) increases the risk of transmitting bloodborne diseases, including the hepatitis C virus (HCV) and human immunodeficiency virus (HIV). Quantifying the characteristics associated with injection-related sharing behaviors and HCV seroprevalence is critical for monitoring trends and addressing drug-related public health concerns within this population. This dissertation presents a secondary data analysis that includes a systematic review and two cross-sectional assessments of data from the Hawai‘i Health & Harm Reduction Center’s (HHHRC) annual syringe exchange program (SEP) survey. The analysis aims to identify factors associated with syringe sharing and injection-related HCV risk behaviors among PWID, with the goal of informing the development of targeted harm reduction strategies and interventions.Study 1 presents a systematic review designed to document and aggregate existing research on needle and drug injection equipment sharing behaviors, as well as injection-related HIV/HCV risk behaviors, in the United States (U.S.). This review covers the period from the initiation of comprehensive needle exchange programs through the years immediately preceding the Coronavirus disease (COVID-19) pandemic (1988–2019). To be included in the review, eligible sources had to be published between January 1, 1988, and December 31, 2019, conducted within the U.S., and written in English. Eligible sources were collected from Ovid MEDLINE®, Web of Science, Education Resources Information Center (ERIC), PsycINFO, Google Scholar, and the Cumulative Index to Nursing and Allied Health Literature (CINAHL) and had to report one or more of the nine pre-defined data items and outcomes. Out of 9,385 sources screened, 1,329 unique research studies spanning 46 U.S. states, two territories, and Washington, D.C., were included. The number of sources reporting on each of the nine outcomes was as follows: 1) syringe sharing (n=1,057); 2) non-syringe drug injection equipment sharing (n=469); 3) drug injection equipment cleaning practices (n=362); 4) syringe-mediated drug-splitting (SMDS) (n=218); 5) having a sharing partner (n=228); 6) having an injection partner (n=266); 7) shooting gallery attendance (n=375); 8) HIV and/or HCV injection serosorting (n=77); and 9) syringe or drug injection equipment reuse (n=138). Study 1 identified inconsistent terminology and the absence of operational definitions in the literature on drug injection equipment sharing and proposed a new, detailed typology for future data collection and reporting on these behaviors. Study 2 utilizes a cross-sectional approach, analyzing SEP data collected by HHHRC between January 1, 2019, and December 31, 2019, including 105 sampled needle exchange clients across four main Hawaiian Islands. Study 2 examines two main binary dependent variables: distributive syringe sharing (yes or no) and receptive syringe sharing (yes or no), both self-reported and recalling the risk period within the previous month. The primary objective was to estimate the prevalence proportions of distributive and receptive syringe sharing and to characterize risk behaviors associated with syringe sharing among needle exchange clients in Hawai‘i. The secondary objective was to examine the relationship between the type of shared drug injection equipment and the directionality of sharing transactions, with the aim of establishing an overall risk profile for sharing behaviors among PWID in Hawai‘i. Self-reported data on independent variables were collected through an interview-administered questionnaire. Log-binomial regressions were employed to estimate crude point prevalence proportions and univariable prevalence proportion ratios (PPRs). A test of independence was conducted to assess the relationship between the hypothesized sharing risk profile, categorized by equipment type and directionality sharing transactions, using cross-tabulation. The overall crude point prevalence proportion of past-month distributive syringe sharing was estimated to be 24.8% (95% confidence interval [CI], 17.4–34%) and past-month receptive syringe sharing had an overall crude point prevalence proportion of 21.8% (95% CI, 14.9–30.8%). Statistically significant correlations were observed between the sharing of syringes, cookers, and cottons. The association between shared equipment type and sharing directionality was statistically significant (P<0.0001). Study 3 also applies a descriptive approach using the same cross-sectional data set as Study 2. The main dependent variable in Study 3 was anti-HCV serostatus (positive or negative), detected through a rapid, point-of-care Food and Drug Administration (FDA)-approved screening test. The primary objective was to estimate the mean point seroprevalence proportion of anti-HCV positivity and to characterize risk behaviors associated with being screened positive for anti-HCV serostatus among needle exchange clients from Hawai‘i. The secondary objective was to estimate the cumulative incidence of HCV infection among those with a known history of seronegative anti-HCV serostatus. Log-binomial regressions were used to estimate prevalence proportion ratios, with and without adjustment for the total duration of engaging in injection drug use. The estimated overall mean crude point seroprevalence proportion of being screened as anti-HCV positive was 54.3% (95% CI, 44.8–63.5%). Among 40 previously seronegative individuals, 10 had incident anti-HCV positive seroprevalence screening results between 2010 and 2019 (cumulative incidence, 25%; 95% CI, 14.2–40.2%). Comparison with 2012 data from the same population and setting showed no significant differences in HCV seroprevalence or incidence. Receptive past-month equipment sharing behaviors were not found to be associated with anti-HCV seroprevalence. The analysis identified age as a confounding variable in the relationship between injection duration and anti-HCV serostatus, suggesting the need for age-specific stratification. Mantel-Haenzel age-adjustment analysis indicated injection duration was significantly associated with screened anti-HCV seropositivity for individuals with more than five years of injection history compared to those with five years or fewer (Mantel-Haenzel PPR=2.12, 95% CI, 1.10–4.08, P=0.007). Study 1 concludes that the findings of this systematic review provide a valuable resource for researchers, health policy leaders, and health service providers to enhance the understanding of syringe sharing and other injection-related HIV/HCV behaviors. This knowledge can be used to optimize harm reduction strategies for individuals who inject drugs. Study 2 highlights the persistence of drug injection equipment sharing in Hawaiʻi, with at least one in five syringe exchange clients reporting sharing in the past month. Study 3 underscores the hyperendemic nature of HCV among PWID in Hawaiʻi, demonstrating ongoing transmission within this population.