Evaluating Network-level Predictors of Behavior Change Among Injection Networks Enrolled in the HPTN 037 Randomized Controlled Trial

Laramie Smith
Steffanie Strathdee, Carl Latkin
Protocol number

HPTN Bibliographic Record

Smith, L. R., Strathdee, S. A., Metzger, D., Latkin, C.. Evaluating network-level predictors of behavior change among injection networks enrolled in the HPTN 037 randomized controlled trial. Drug Alcohol Depend. 2017, 175: 164-170.


BACKGROUND: Little is known about ways network-level factors that may influence the adoption of combination prevention behaviors among injection networks, or how network-oriented interventions might moderate this behavior change process. METHODS: A total of 232 unique injection risk networks in Philadelphia, PA, were randomized to a peer educator network-oriented intervention or standard of care control arm. Network-level aggregates reflecting the injection networks' baseline substance use dynamics, social interactions, and the networks exposure to gender- and structural-related vulnerabilities were calculated and used to predict changes in the proportion of network members adopting safer injection practices at 6-month follow-up. RESULTS: At follow-up, safer injection practices were observed among 46.31% of a network's members on average. In contrast, 25.7% of networks observed no change. Controlling for the effects of the intervention, significant network-level factors influencing network-level behavior change reflected larger sized injection networks (b=2.20, p=0.013) with a greater proportion of members who shared needles (b=0.29, p<0.001) and engaged in poly drug use at baseline (b=6.65, p=0.021). Changes in a network's safer injection practices were also observed for networks with fewer new network members (b=-0.31, p=0.008), and for networks whose members were proportionally less likely to have experienced incarceration (b=-0.20, p=0.012) or more likely to have been exposed to drug treatment (b=0.17, p=0.034) in the 6-months prior to baseline. A significant interaction suggested the intervention uniquely facilitated change in safer injection practices among female-only networks (b=-0.32, p=0.046). CONCLUSIONS: Network-level factors offer insights into ways injection networks might be leveraged to promote combination prevention efforts.