Diagnostic accuracy of rapid antigen test for malaria and determinants of heavy malaria parasitaemia in children at the Nnamdi Azikiwe University Teaching Hospital, Nnewi, Nigeria

Abstract

Background: According to the United Nations Children's Fund, malaria kills a child every 30 s and about 3000 every year. Ninety per cent of the global burden of malaria occurs in sub-Saharan Africa. To reduce this burden, prompt recognition of risk factor, rapid diagnosis and immediate treatment are crucial. Objective: This study evaluated the diagnostic accuracy of rapid diagnostic test (RDT) used in the diagnosis of malaria. It secondarily sought to determine factors that are associated with heavy malaria parasitaemia in children. Methodology: This cross-sectional and descriptive study was conducted over a 5-month period. Children aged 6 months to 17 years, who had axillary temperature >37.4°C or history of fever in the past 48 h and who had not received a full course of artemisinin combination therapy were included. The patients were enrolled consecutively using purposive sampling methods. Blood samples for malaria parasite were collected from all participants using microscopy and RDT. Results: Of the 246 participants enrolled, 58 and 188 tested positive and negative for malaria parasite using blood film microscopy (BFM). Of the 58 positive and 188 negative blood samples, 49 and 157 participants, respectively, were reactive and non-reactive for malarial antigen when the RDT was done. This gave RDT sensitivity of 84.5% (95% confidence interval [CI]: 80.3-88.7), specificity of 83.5% (95% CI: 81.1-85.9), false-positive rate of 16.5% (95% CI: 3.8-29.2), false-negative rate of 15.5% (95% CI: 11.9-42.9), positive predictive value of 61.3% (95% CI: 52.4-70.2) and negative predictive value of 94.6% (95% CI: 93.8-95.4). The overall diagnostic accuracy of the RDT was 83.8% (95% CI: 81.7-85.9). None of the respondent's clinicodemographic factors such as age, place of residence, socio-economic status, degree and duration of fever were significantly associated with heavy malaria parasitaemia in surveyed children. Conclusion: The RDT is a good diagnostic tool and can be conveniently used in situation where rapid diagnosis of malaria parasitaemia is needed and/or where BFM is unavailable.