Evaluation of CareStart™ malaria HRP2/pLDH (Pf/PAN) combo rapid diagnostic test for diagnosis of Plasmodium falciparum infection in malaria co-endemic areas in association with parasite density
Christian M., Ekawati LL., Pratama AR., Cahyaningati S., Bere HK., Rustam M., Kalbuadi I., Andini J., Yuliana J., Fadilah I., Ley B., Thriemer K., Price RN., Sutanto I., Baird JK.
Abstract Background As a widely accepted field standard diagnostic tool for malaria, microscopic examination is often difficult to perform in resource-poor settings. The immunochromatographic HRP2/pLDH (Pf/Pan) Rapid Diagnostic Tests (RDTs) serve as alternatives to microscopic examination for falciparum and non-falciparum malaria in co-endemic areas by detecting the histidine-rich protein 2 (HRP2) and pan-plasmodial lactate dehydrogenase (pLDH) antigen. However, Pf/Pan RDTs do not directly quantify parasitaemia. In this study, the diagnostic performance of Pf/Pan RDT and its association with parasite density was examined. Methods Blood smears from patients who were screened for PRIMA Clinical Trial (Trial Registration Number: NCT03916003) conducted in East Sumba, Indonesia, and enrolled to its sub-study, ACROSS, were examined for microscopic examination and RDT using CareStart™ Malaria HRP2/pLDH (Pf/PAN) Combo (CareStart™ Pf/Pan RDT). Results were analysed for both diagnostic performance of RDT and its relationship with parasite density using a logistic regression model. Results 317 participants were included in this study and 158 (49.8%) were malaria positive by microscopy. Among all malaria-positive participants, Plasmodium falciparum infections accounted for 149 (94.3%) cases. The sensitivity and specificity of HRP2 band were 97.3% (95% CI 93.3–99.2) and 97.6% (95% CI 94.0–99.4), respectively, while that of pLDH band were 87.3% (95% CI 81.1–92.0) and 100% (95% CI 97.7–100). For each ten-fold increase in parasite density, the RDT had 12 times the odds of returning Pf/Pan-positive results (n = 126) compared to Pf-positive (n = 19) (OR: 12.1; 95% CI 5.18 to 34.8; p < 0.001). Conclusions CareStart™ Pf/Pan RDT is reliable in diagnosing falciparum malaria and Pf/Pan-positive results indicate higher parasite density. Pf/Pan-positive results should alert the clinical staff of the increased risk of poor clinical outcome, and should be prioritized for microscopic examination compared to Pf-positive results.