Outcome Measures



Syringe exchange use; hepatitis B and C infection.

75% of case patients with hepatitis B and 26% of control subjects had never used the exchange; similar proportions were found for the hepatitis C case and control groups. After adjustment for demographic characteristics and duration of drug use, nonuse of the exchange was associated with a six-fold greater risk of hepatitis B (OR=5.5; 95% CI: 1.5–20.4) and a sevenfold greater risk of hepatitis C (OR=7.3; 95%CI: 1.6–32.8).

  • Source population were IDUs in Pierce County (Washington) and were at risk for developing hepatitis B or C.

  • May have been differences between the injection practices of cases and controls which may have resulted in uncontrolled confounding.

  • Cases and controls may have differed in their use of other strategies (bleach, syringe purchase in pharmacies, etc.) to prevent infection.

  • The Tacoma syringe exchange’s role as the primary source of HIV prevention for local IDUs may have contributed to the magnitude of the association between syringe exchange and risk of viral hepatitis.

Determinants of HIV seroconversion.

Multivariate analysis showed borrowing syringes, unstable housing, and injecting ≥ 4 times daily to be independently associated with seroconversion. Protective associations were found between sex with opposite gender and tetrahydrocannabinol use.

  • Cases may have had differential recall of events than controls.

  • Self-reported data.

  • Study focused on incident cases of HIV and systematically excluded populations in which HIV is already highly prevalent.

  • Statistical power was limited with respect to ability to do subgroup analyses.

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