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Malaria Rapid Diagnostic Test: A Study of Accuracy among Adults in North Central Nigeria
Abstract
Background: There is increasing need for parasitological diagnosis of malaria in order to direct rational therapy and reduce the consequences of presumptive treatment. Because microscopy, the gold standard test, is laborious and technically difficult to perform, we evaluated the accuracy of a Rapid Diagnostic Test (RDT) that could be widely deployed for testing.
Methodology: A hospital based cross-sectional study in which out-patients older than 15 years with presumptive (clinical) diagnosis of malaria from February to May 2010 were consecutively tested. Capillary blood from each consenting patient was tested for Plasmodium falciparum infection by both conventional Giemsa stain microscopy and Histidine Rich Protein-2 (HRP-2) rapid diagnostic testing. The statistical test applied were mean ± SD for continuous variables and proportions for categorical variables as well as the estimation of accuracy of RDT. A p-value < 0.05 was considered statistically significant, and agreement (kappa statistics) between RDT and microscopy provided estimation of reliability of the RDT; > 80% was considered good reliability.
Results: A total of 161 patients were studied. The mean age was 30.0 ± 11.4 years with 116 (72%) females and 45 (28%) males; p<0.05. Nine (5.6%) and 10 (6.2%) patients had parasitaemia on microscopy and RDT testing respectively. The microscopy results were in agreement with the RDT results in 160(99%) patients. The sensitivity and specificity of the RDT were 100% and 99.3% respectively while the positive and negative predictive values were 90% and 100% respectively.
Conclusion: The RDT was highly sensitive for the detection of parasitaemia and could be useful in the accurate diagnosis of Plasmodium falciparum malaria.
Methodology: A hospital based cross-sectional study in which out-patients older than 15 years with presumptive (clinical) diagnosis of malaria from February to May 2010 were consecutively tested. Capillary blood from each consenting patient was tested for Plasmodium falciparum infection by both conventional Giemsa stain microscopy and Histidine Rich Protein-2 (HRP-2) rapid diagnostic testing. The statistical test applied were mean ± SD for continuous variables and proportions for categorical variables as well as the estimation of accuracy of RDT. A p-value < 0.05 was considered statistically significant, and agreement (kappa statistics) between RDT and microscopy provided estimation of reliability of the RDT; > 80% was considered good reliability.
Results: A total of 161 patients were studied. The mean age was 30.0 ± 11.4 years with 116 (72%) females and 45 (28%) males; p<0.05. Nine (5.6%) and 10 (6.2%) patients had parasitaemia on microscopy and RDT testing respectively. The microscopy results were in agreement with the RDT results in 160(99%) patients. The sensitivity and specificity of the RDT were 100% and 99.3% respectively while the positive and negative predictive values were 90% and 100% respectively.
Conclusion: The RDT was highly sensitive for the detection of parasitaemia and could be useful in the accurate diagnosis of Plasmodium falciparum malaria.
