Validation of Malaria Antigen Detecting Rapid Diagnostic Test Kit: A Study from Highly Endemic Area in Coastal India

Abstract

Introduction: Malaria Rapid Diagnostic Test (MRDT) is widely used for diagnostic purposes in endemic areas and resource-constrained settings. However, concern about the accuracy of RDTs has made its wide-scale usage a debatable issue. Aim: To assess the validity of antigen detecting MRDT kits by comparing the test results with that of conventional Peripheral Smear (PS) examination used for diagnosis of malaria. Materials and Methods: The present cross-sectional study was done in Mangalore city which is highly endemic for Plasmodium vivax and falciparum malaria. It was conducted from May to September 2017 which corresponds to the peak season of malaria in Mangalore. The validity of antigen detecting MRDT kit namely SD Bioline Malaria Antigen test kit (Standard Diagnostics Inc., India) as a screening test was compared with a gold standard test namely Giemsa stained thick and thin blood film microscopy. Results: Out of the total 309 cases, 210 (68%) tested positive by PS examination. MRDT showed a sensitivity of 98.6%, specificity of 86.9%, Positive Predictive Value (PPV) of 94.1% and Negative Predictive Value (NPV) of 96.6%. False Positive (FP) rate of the test was 13.1% and False Negative (FN) rate was 1.4%. The accuracy rate of the screening test was 94.8%, positive likelihood ratio was 7.53, negative likelihood ratio was 0.016 and Diagnostic Odds Ratio (DOR) was 470.6. Sensitivity and specificity of the screening test were higher in the age group of less than 18 years compared to higher age groups. Sensitivity and NPV of the screening test were higher while PPV was lesser for diagnosing Plasmodium falciparum malaria compared to Plasmodium vivax malaria. Area under receiver operating characteristic curve for MRDT was 0.927 when compared with the gold standard test. Conclusion: Antigen detecting MRDT showed good performance as a screening test and hence can be recommended for wide-scale usage at this settings.