The correlation between malaria RDT (Paracheck pf.®) faint test bands and microscopy in the diagnosis of malaria in Malawi
- PMID: 28464837
- PMCID: PMC5414284
- DOI: 10.1186/s12879-017-2413-x
The correlation between malaria RDT (Paracheck pf.®) faint test bands and microscopy in the diagnosis of malaria in Malawi
Abstract
Background: Faint test bands of Paracheck Pf.® are interpreted as malaria positive according to world health organization (WHO) guideline. However if there are conspicuous number of faint test bands, a performance of Paracheck Pf.® could be influenced depending on whether interpreting faint test bands as malaria positive or negative. Finding out the frequency and accurate interpretation of faint test bands are important to prevent the overdiagnosis and drug resistance.
Methods: A cross-sectional, descriptive study was conducted to find out the frequency of faint test bands and evaluate the performance of Paracheck Pf.® by sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy of diagnosis of Paracheck Pf.® using microscopy as the gold standard. 388 suspected patients with malaria in Malawi were recruited in this study. Malaria rapid diagnostic tests (RDTs) and microscopy were used and patients' information which includes age, sex, body temperature and signs or symptoms of malaria were recorded.
Results: Among all patients involved in the study, 29.1% (113/388) were found malaria positive by RDT. Overall 5.4% (21/388) of all Paracheck Pf.® tests resulted in a "faint test band" and 85.7% (18/21) corresponded with malaria negative by microscopy. Faint test bands which corresponded with malaria positive by microscopy were lower parasite density and there are no patients who showed definitive symptom of malaria, such as fever. When Paracheck Pf.® "faint test bands" were classified as positive, accuracy of diagnosis was 76.5% (95% CI 72%-80.7%) as compared to 80.4% (95% CI 76.1%-84.2%) when Paracheck Pf.® "faint test bands" were classified as negative.
Conclusions: This study shows that frequency of faint test bands is 5.4% in all malaria RDTs. The accuracy of diagnosis was improved when faint test bands were interpreted as malaria negative. However information and data obtained in this study may not be enough and more intensive research including a frequency and property of faint test bands is needed for significant interpretation of faint test bands.
Keywords: Accuracy of diagnosis; Faint test band; Malaria rapid diagnostic test; NPV; PPV; Paracheck pf.®; Sensitivity; Specificity.
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References
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- Malawi Government Ministry of Health National Malaria Control Program. Malawi Malaria Indicator Survey, 2012. [https://dhsprogram.com/pubs/pdf/MIS13/MIS13.pdf] Accessed 15 December 2014.
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- World Health Organization. World Malaria Report 2014. [http://www.who.int/malaria/publications/world_malaria_report_2014/en/] Accessed 21 December 2014.
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- Foundation for Innovative New Diagnostics. Malaria Rapid Diagnostic Test: An implementation guide. [https://www.ghdonline.org/uploads/malaria_rdt_implementation_guide2013.pdf] Accessed 27 December 2014.
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- United States Agency for International Development. President’s Malaria Operation Plan FY 2014.[https://www.pmi.gov/docs/default-source/default-document-library/malaria...] Accessed 18 January 2015.
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