The goal of this clinical trial is to assess the effectiveness of an evidence-based, organizational-level implementation strategy, the Systems Analysis and Improvement Approach, in improving HIV service delivery (SAIA-SSP-HIV) in U.S. syringe services programs (SSPs). The main questions it aims to answer are:

• Does SAIA-SSP-HIV improve delivery of HIV services (including the proportion of SSP participants receiving HIV testing and referrals to appropriate clinical services for HIV prevention and treatment) compared to implementation as usual (IAU)?
• Does SAIA-SSP-HIV result in sustained improvement of HIV service delivery cascades (including the proportion of SSP participants receiving HIV testing and referrals to appropriate clinical services for HIV prevention and treatment) compared to IAU?
• What are the costs associated with SAIA-SSP-HIV and how cost-effective is the strategy?

The trial will take place over 21 months and consist of a 3-month lead-in period, a 12-month active period, and a 6-month sustainment period. During the 12-month active period a SAIA specialist will meet with SSPs randomized to the SAIA-SSP-HIV arm to help them optimize their HIV service delivery cascades. Researchers will compare the SAIA-SSP-HIV and IAU arms to see if HIV service delivery and costs and cost-effectiveness differ by group.

The investigators plan to examine SAIA-SSP-HIV's impact on SSPs compared to an implementation-as-usual (IAU) condition across 3 aims and several related hypotheses. Data collection will take place monthly across 21 months of SSP participation. These 21 months include a 3-month lead-in period to establish SSP outcome data characteristics, the 12-month intervention period during which sites randomized to SAIA-SSP-HIV will meet with the SAIA specialist, and an additional 6 months (sustainment period) to determine whether impacts are sustained.

• Aim 1. The first aim of the study is to assess the effectiveness of SAIA-SSP-HIV. The investigators hypothesize that compared with SSPs receiving IAU, SSPs receiving SAIA-SSP-HIV will significantly increase the proportion of SSP participants receiving HIV testing and referrals to appropriate clinical services for HIV prevention and treatment over 12 months.
• Aim 2. The second aim of the study is to assess the sustained effectiveness of SAIA-SSP-HIV. The investigators hypothesize that compared with SSPs that received IAU, SSPs that received SAIA-SSP-HIV will report a significantly higher proportion of SSP participants receiving HIV testing and referrals to appropriate clinical services for HIV prevention and treatment at 18 months.
• Aim 3. The third aim of the study is to assess the costs and cost-effectiveness of SAIA-SSP-HIV on improving HIV service delivery cascades at SSPs, relative to IAU. The investigators hypothesize that, compared to SSPs that received IAU, SSPs that received SAIA-SSP-HIV will be cost-effective at increasing the proportion of SSP participants receiving HIV testing and referrals to appropriate clinical services for HIV prevention and treatment.

To meet these aims, the investigators plan to conduct a randomized controlled interrupted time series trial among 32 U.S. SSPs (n=16 will be randomly assigned to the SAIA-SSP-HIV arm and n=16 to the IAU arm). SSPs randomized to the IAU arm will not receive support from a SAIA-SSP-HIV specialist. As such, the IAU condition is characterized by the absence of SAIA-SSP-HIV with the goal of comparing whether SAIA-SSP-HIV improves SSPs' HIV service delivery cascade.

Preliminary research has demonstrated the need for increased HIV services at SSPs and the acceptability, facilitators, and feasibility of HIV service implementation at SSPs. To the investigators' knowledge, this will be the first randomized controlled trial (RCT) of an organizational-level intervention to optimize the SSP-based HIV service delivery cascade. If successful, SAIA could be disseminated to the ≥430 SSPs nationally and in global settings, carrying the potential for exceptional impact amidst persistent HIV transmission in people who inject drugs (PWID).

The primary contact at each SSP will be asked about basic organizational characteristics (location, number of staff, budget, etc.). Next, the primary contacts as well as other staff involved with HIV service delivery at each SSP will be asked about contextual variables such as implementation climate for improving the HIV service delivery cascade. Quality control and monitoring of SAIA fidelity will include reviewing the SAIA management database for content, which will contain key information regarding SAIA specialists' delivery of the SAIA intervention to SSPs (e.g., date, service type and length, activity and name of SAIA specialist). The database will be reviewed during weekly meetings between the SAIA specialists and the study coordinator. Additionally, the SAIA specialists and study coordinator will review implementation efforts by completing periodic reflections on a monthly basis. If necessary, additional training and supervision will be conducted with the SAIA specialists. For SSPs in the SAIA arm, the investigators will routinely collect data on the number of SAIA cycles and the content and impact of programmatic changes during the active and sustainment periods to allow for observation of activities during and after SAIA delivery.

Inclusion Criteria:

• Organization operates within the United States, U.S. territory, or Tribal Nation.
• Organization operates a dedicated syringe service program (SSP) that provides access to sterile syringes and injection equipment for people who inject drugs (PWID).
• In the past 30 days, SSP staff have directly provided HIV counseling and testing services to SSP participants.

Exclusion Criteria:

• Organization is participating in or has participated in other studies involving SAIA or components of SAIA.
• Organization intends to stop providing HIV counseling and testing services to SSP participants within 21 months of their respective start date.