To achieve global goals for the treatment of HIV, many countries are piloting and scaling up differentiated service delivery models (DSD). A handful of efforts have been formally described and evaluated in the literature; many others are being implemented formally or informally under routine care, without a research or evaluation goal. For most countries however, the investigators have little evidence on progress and challenges at the facility level-the number of patients actually participating in DSD models, health outcomes and non-health outcomes, effects on service delivery capacity and clinic efficiency and operations, and costs to providers and patients.

Alternative Models of ART Delivery: Optimizing Benefits (AMBIT) is a set of data synthesis, data collection, and data analysis activities aimed at generating information for near- and long-term decision making and creating an approach and platform for ongoing evaluation of differentiated models of HIV treatment delivery. The first AMBIT protocol, "Gathering Records to Evaluate Antiretroviral Treatment" (GREAT, Zambia Ref. No. 2019-Sep-030), collects and analyzes comprehensive patient medical record data, allowing us to assess the effect of DSD models on patients' clinical outcomes and to evaluate uptake of DSD models at scale.

The Sentinel-Zambia study, the second AMBIT protocol, is examining the effect of DSD models on patient and provider satisfaction, service delivery capacity and quality, costs to patients, and other outcomes for which data are not routinely collected in patient-level medical records. The first round of Sentinel-SA was conducted in 2021. The AMBIT 2.0 protocol will allow up to four additional annual rounds of data collection, in 2022-2025. The investigators collected clinic aggregate data, conducted surveys of patients and providers, and observed operations at a selected set of 12 Zambian healthcare facilities and their affiliated DSD models in Round 1. Round 2 (2022) and later rounds will collect the same types of data at 12 facilities in Zambia and will expand the study's research questions to include differentiated models of HIV testing and linkage to care. Results are expected to inform Zambian policy makers and other local and international stakeholders on the actual implications of DSD models for patients, health system operations, and healthcare budgets.

Inclusion Criteria:

Inclusion criteria for the time and motion study are:

• Patient-facing or patient-supporting service provider at the study site (patient-supporting providers include data clerks, pharmacists, etc.)
• Directly or indirectly involved in the site's implementation of ART and DSD models
• Employed in current role at the study site for at least six months
• Provides written informed consent to participate

Inclusion criteria for provider interviews are:

• Direct or indirect service provider at the study site (indirect providers include supervisors, technical advisors, etc.)
• Directly or indirectly involved in the site's implementation of ART and DSD models
• Employed in current role at the study site for at least six months
• Provides written informed consent to participate.

Inclusion criteria for the patient survey are:

• Living with HIV and on ART for at least six months at the study site
• ≥ 18 years old (18 and older considered adult for research purposes in Zambia)
• Enrolled in a specified model of care (including conventional care) up to the target number of participants for that model and have received at least one medication refill under this model
• Provide written informed consent to participate.

Inclusion criteria for the testing survey are:

• Undergoing HIV testing at the study site or other testing site within the catchment area
• ≥ 18 years old (18 and older considered adult for research purposes in Zambia)
• Provide written informed consent to participate.

Exclusion Criteria:

Exclusion criteria for the time and motion study are:

● None.

Exclusion criteria for provider interviews are:

● None.

Exclusion criteria for the patient survey are:

• Unable to communicate in any of the languages into which the questionnaire has been translated or that is known to the research assistant
• Not physically, mentally, or emotionally able to participate in the study, in the opinion of the investigators or study staff.
• Unwilling to take the time required to complete the questionnaire on the day of consent.

Exclusion criteria for the testing survey are:

• Unable to communicate in any of the languages into which the questionnaire has been translated or that is known to the research assistant
• Not physically, mentally, or emotionally able to participate in the study, in the opinion of the investigators or study staff.
• Unwilling to take the time required to complete the questionnaire on the day of consent.

Clients using the Zambian public health system and providers employed by that system.

Data that are collected by the study will be made available after protocol closure. Data that are owned by others (e.g. the National Department of Health) cannot be shared by the authors.

Within one year of protocol closure.