How to ensure effective and sustainable ILI surveillance in Belgian general practices? : protocol

In Belgium, the COVID-19 Barometer in General Practices (cBGP), a semi-automated tool, was rapidly set up to support the surveillance of COVID-19 by extracting data from the Electronic Medical Records (EMR) of General Practitioners (GPs). Hence, the cBGP enabled a high GP participation rate and the rapid follow-up of COVID-19. Concurrently, the instrument collected data on Influenza-like Illness (ILI) as an early marker of COVID-19 activity. This extraction-based surveillance system could take over the registration of ILI cases currently done by the Belgian Sentinel General Practitioners network (SGP). In order to identify the most suitable alternative for effective and long-term surveillance of ILI, the current study is investigating the contribution and limitations of using the code-based cBGP as a replacement for the questionnaire-based SGP system to monitor the syndrome. An observational retrospective study covering 3 influenza seasons from 2021 to 2024 is being carried out. Both qualitative and quantitative outcome measures are determined to gather evidence on the systems’ performance, based on nine attributes namely: Data Quality, ILI Incidence, Sensitivity, Representativeness, Timeliness, Acceptability, Simplicity, Stability and Flexibility. The methodological framework relies on the Centers for Disease Control and Prevention (CDC) guidelines for evaluating public health surveillance systems and the Simple Multi-Attribute Rating Technique (SMART) is used to facilitate the decision-making process of an appropriate alternative. Three alternatives are given a value according to the score and the weight-related importance of attributes by a group of experts. The alternative with the higher endorsement is then considered as the preferable one and recommendations for implementation are formulated. This combined approach, which blends performance analysis and multi-criteria decision analysis, allows for a sound and reproducible comparison of systems. Moreover, while the Covid-19 pandemic has accelerated the development of a national code-based system, this study aims to start redefining the role of the barometer in insuring robust disease surveillance. This protocol could serve as a basis for validating other syndromic surveillance data from extraction-based systems in primary care.