Abstract / Summary
Malaria remains a major public health challenge in Ethiopia, and improved clinical care supported by innovative diagnostic tools is essential for elimination efforts. The Sysmex XN-31 automated hematology analyzer, which detects and quantifies malaria-infected red blood cells, was evaluated in clinical settings for malaria diagnosis in Ethiopia. A hospital-based cross-sectional study was conducted from April to September 2024 at two public hospitals in Ethiopia. Febrile outpatients suspected of malaria were enrolled after providing consent. Capillary blood was collected for routine microscopy, and 4 mL of venous EDTA blood was obtained for rapid diagnostic tests (RDTs), Sysmex XN-31 analysis, and qPCR. Sysmex XN-31 performance was assessed against expert microscopy and qPCR. Statistical analyses were performed using SPSS 27 and MedCalc v23. Diagnostic parameters (sensitivity, specificity, and predictive values) were calculated with 95% confidence intervals, and hypothetical community prevalence rates (5%, 25%, and 50%) were modeled. Usability of the Sysmex XN-31 was evaluated at both sites, with statistical significance assessed using Fisher’s exact test. Agreement between tests was measured using kappa statistics. Parasitemia quantification was compared using Bland–Altman and Passing-Bablok regression. Among 400 suspected febrile cases, malaria positivity was 22.2% (n = 89), 21% (n = 84), 19.2% (n = 77), 18.8% (n = 75), and 16.2% (n = 65) by PCR, Sysmex XN-31, expert microscopy, field microscopy, and RDTs, respectively. Sysmex XN-31 sensitivity and specificity were 93.5% (95% CI 88.0, 99.0) and 96.6% (95% CI 94.2, 98.4), compared with expert microscopy. Using PCR as the reference, sensitivity decreased to 84.3% (95% CI 80.7, 87.8), while specificity increased slightly to 97% (95% CI 95.3, 98.7). Under hypothetical community prevalence scenarios, the Sysmex-XN-31 demonstrated high negative and positive predictive values relative to field microscopy and RDTs. Substantial agreement was observed between Sysmex XN-31 and field microscopy [89.8%, kappa = 0.68 (0.61–0.80)]. The analyzer also showed strong near-perfect agreement with RDTs [92.5%, kappa = 0.74 (0.61–0.80)] and PCR (93.8% agreement, kappa = 0.81 [0.81–1.00]). Bland–Altman and Passing-Bablok regressions showed no significant differences ( p > 0.05) in parasite quantification between Sysmex XN-31 and microscopy. Usability testing showed that the analyzer can be operated with minimal training, with no statistically significant differences across educational backgrounds or professions (Fisher’s exact test, p > 0.05). The Sysmex XN-31 automated hematology analyzer demonstrated high sensitivity and specificity compared to expert microscopy and PCR, offering substantial value for malaria surveillance and elimination efforts. Although further calibration was needed for parasite quantification, the analyzer provided rapid malaria detection alongside routine CBC results.