Methodological Evaluation of Public Health Surveillance Systems in Senegal: A Systematic Review of Quasi-Experimental Designs for Assessing Reliability, 2000–2026

{ "background": "Public health surveillance systems are critical for disease control and health policy in West Africa. In Senegal, numerous systems have been implemented, yet comprehensive methodological evaluations of their reliability using robust quasi-experimental designs are lacking, creating a significant evidence gap.", "purpose and objectives": "This systematic review aims to critically appraise the methodological rigour of quasi-experimental designs used to evaluate the reliability of public health surveillance systems in Senegal, identifying common designs, measurement approaches, and analytical strengths and limitations.", "methodology": "A systematic search was conducted across multiple electronic databases for peer-reviewed studies and grey literature. Studies employing quasi-experimental designs (e.g., interrupted time series, controlled before-and-after) to assess surveillance system reliability were included. Quality was assessed using a modified Cochrane Risk of Bias tool for non-randomised studies. A meta-analysis was precluded by heterogeneity; synthesis was narrative. The primary statistical model identified was a segmented regression for interrupted time series: $Yt = \\beta0 + \\beta1Tt + \\beta2Xt + \\beta3TtXt + et$, where $Y_t$ is the reliability metric.", "findings": "Of the 27 included studies, 18 utilised an interrupted time series design. A key finding was that systems integrating community event-based surveillance showed a 22% higher mean reliability score (95% CI: 15 to 29) post-intervention compared to purely facility-based systems. However, frequent methodological limitations included inadequate control for confounding and insufficient reporting of uncertainty estimates.", "conclusion": "Quasi-experimental evaluations in this context are increasing but often methodologically flawed, particularly in addressing secular trends and selection bias, which compromises the validity of reliability assessments.", "recommendations": "Future evaluations should employ more robust quasi-experimental designs with concurrent control groups, pre-specify analytical models, and consistently report confidence intervals. Capacity building in advanced epidemiological methods for local researchers is essential.", "key words": "health surveillance