Real-World Performance of HRP2-Based Malaria RDTs Compared to Microscopy Routinely Utilized in Port Harcourt Metropolis, Rivers State, Nigeria

Abstract

Background: Accurate and timely diagnosis of malaria is essential for effective case management, particularly in endemic regions such as Nigeria. Rapid Diagnostic Tests (RDTs) based on the detection of Plasmodium falciparum Histidine-Rich Protein 2 (HRP2) are widely used in health facilities due to their simplicity and speed. However, variability in their diagnostic performance, especially in field conditions, necessitates local validation. This study evaluated and compared the diagnostic performance of two HRP2-based RDTs commonly used in healthcare settings in Port Harcourt, Rivers State, Nigeria. Methods: A cross-sectional diagnostic accuracy study was conducted from February 2024 to March 2025, in seven (7) randomly selected health facilities in Port Harcourt. Febrile patients aged ≥ 12 months who presented with symptoms suggestive of malaria were enrolled. Blood samples were tested using two HRP2-based RDTs. Thick/thin blood films were prepared for expert microscopy, which served as the reference standard. Diagnostic performance metrics-sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV)-were calculated with 95% confidence intervals. Results: A total of 829 participants were enrolled, with a malaria prevalence of 33.3% (276/829) by microscopy and 30.2% (250/829) by RDTs. Plasmodium falciparum infection was highest among participants aged 11-20 years (47.3%) compared to other age groups (χ²=20.68, df=6, P=.002) while infection was slightly higher among females (33.3%) compared to males (χ²=2.74, df=1, P=.098). Both RDTs demonstrated a sensitivity of 91%, specificity of 100%, PPV of 100%, and NPV of 96%. Cohen’s kappa indicated excellent agreement between both RDTs and microscopy (κ = 0.93). Conclusion: Both HRP2-based RDTs demonstrated acceptable diagnostic performance and can support routine malaria diagnosis in Port Harcourt health facilities. These findings underscore the importance of local performance evaluations of RDTs to guide procurement and clinical use. Further research is recommended to assess the impact of HRP2 gene deletions on RDT accuracy.The public health relevance of these findings is enhanced diagnostic validation of HRP2-based RDTs in field conditions utilized in government healthcare facilities in Rivers State.