Case-Based Surveillance (CBS)
What is CBS?
HIV case-based surveillance (CBS) means keeping track of people who get HIV.
Usually beginning with:
- The report of the first HIV infection diagnosis
- Including defined sentinel events from every person diagnosed with HIV
- Monitored by a public health agency responsible for monitoring and controlling the epidemic
This creates a long-term record of every person who is found to have HIV, which is sent from the place where services are given to a central database for epidemiological analysis.
For HIV, the key to successful CBS is making sure that the data from different systems about the HIV sentinel events (listed below) are combined for each patient.
Case-based surveillance data are used to track how much a disease is affecting people and to guide public health actions.
Sentinel Events
- HIV Diagnosis
- Entry to Care
- ART Initiation
- ART Regimen Change
- First/Baseline CD4 count
- VL Suppression
- Death and Cause of Death
The following diagram illustrates the sentinel events with example visit scenarios.
Why CBS?
Typically, patient monitoring data are consolidated at the facility level before being forwarded up the health system.
- This system provides reasonably robust estimates of progress against important metrics.
- However, aggregate reporting doesn't track program efficacy with individual-level longitudinal data.
Because aggregate data cannot be disaggregated into individual-level data, the aggregated record may have lower data quality
- For example, duplicate entries cannot be detected, which may overestimate the number of persons diagnosed with HIV and accessing services.
- Patient tracking between institutions or systems is also impossible, compromising reporting quality.
CBS solves some of these constraints by collecting individual HIV statistics.
- Each case is tracked throughout its lifecycle, and information can be linked by name, ID code, or other characteristics.
- This makes it possible to track across systems (i.e. reducing the false duplicates when compared to collecting pre-aggregated data across facilities).
- AND, CBS systems still protect patient privacy.
What is required to implement CBS?
Step 1 - Requirements Analysis, Approach & Policies
- Develop requirements
- Determine the architectural approach to link together disparate health information systems.
- Establish policies
Step 2: Identify critical technical components for CBS?
To achieve this, you will need:
- Minimum Dataset
- Client Registry/Master Patient Index
- Patient Deduplication
- Data Repository
- Interoperability Layer
Step 3: Determine health information systems that need to connect for CBS?
- Civil Registration Systems
- HIV Testing Systems
- Laboratory Information Systems
- Pharmacy Information Systems
- Point of Service Systems (EMR)
- Paper Record Systems
NOTE: Through the Data Integration and Strategies and Implementation (DISI) project, which was funded by PEPFAR, a large number of products have been made that countries can use to implement the important parts of CBS.
