Impact of the introduction of GeneXpert on pulmonary tuberculosis detection trends in Guinea: analysis of the WHO “TB Burden” database (2000–2024)

Abstract Background Tuberculosis screening is an essential first step in the early identification of cases, prevention of transmission, and initiation of prompt treatment. GeneXpert, introduced in Guinea in 2012, offers high sensitivity and specificity for tuberculosis diagnosis. The PNLT current policy is to expand the use of the GeneXpert test as the initial nationwide diagnostic test. Therefore, the objective of this study was to evaluate the impact of the introduction of GeneXpert on pulmonary tuberculosis detection trends in Guinea. Methods We conducted an ecological interrupted time-series study using 25 annual country-level observations (Guinea, 2000–2024). The introduction of GeneXpert MTB/RIF was considered the intervention. Tuberculosis incidence per 100,000 population and case detection rate were analysed using segmented linear regression to assess changes in level and trend after implementation. Subsequently, the “CausalImpact” package in R was used to estimate the causal effect of the intervention by comparing observed post-intervention outcomes with Bayesian model-based counterfactual predictions. Results The detection rate remained stable prior to the introduction of GeneXpert in 2012 (β = 0.23; p = 0.526) and showed no significant immediate change (β = 0.57; p = 0.870). In contrast, a gradual and significant increase in this rate was observed after the intervention (β = 1.79, p = 0.001). Regarding the incidence per 100,000 inhabitants, an upward trend was observed prior to 2012 (β = 3.73; p < 0.001), followed by a significant immediate drop upon the introduction of GeneXpert (β = -12.60; p = 0.043), with no significant change in the long-term trend (β = -0.38; p = 0.646). Bayesian CausalImpact analysis showed a mean increase in the detection rate of 13.96 pp following the introduction of GeneXpert, representing a relative rise of 27% (95% CI: 19–36%; p = 0.001). Conclusion These results support the expansion of this technology at the district level to improve the tuberculosis case detection system in Guinea. The results suggest the value of continuing to invest in tuberculosis diagnostic capacities in Guinea, particularly by expanding GeneXpert platform coverage and strengthening healthcare worker training to improve the case detection.