Diagnostic Performance of Blood Film Microscopy and PfHRP2-based RDT in a Routine Clinical Setting of a Secondary Health Facility in Ghana

Abstract

Background: Malaria remains a major public health threat claiming many lives particularly in Sub-Saharan Africa. Light microscopy and RDT are the mainstay tests in the clinical settings for malaria diagnosis. Many studies report varying levels of validity of these tests compared to molecular methods like PCR. Documentation on such comparative study involving the use of molecular techniques as reference test is scanty in Ghana. This study therefore assesses the diagnostic performance of these tests compared to PCR. Methods: Blood film microscopy (thin and thick), RDT and nested PCR were run on blood samples from a total of 188 malaria suspected patients. The accuracy indices of the microscopy and RDT were calculated using the results of the PCR as the reference test. Results: A total of 188 patients were recruited with females constituting the majority 128 (68%). The paediatric age group 1-10 years carried the largest burden of malaria by means of all the 3 tests. A sensitivity of 47.37% (95% ci, 37.03 – 57.88%) was shown by both the microscopy and RDT with specificity of 93.55% (95% ci, 86.48 – 97.60) and 100% (95% ci, 96.11 – 100.00%) and kappa co – efficient of 0.41 and 0.47 respectively. Conclusion: Both microscopy and RDT exhibited high level of specificity but low sensitivity. Significant number of malaria parasitaemic patients as revealed by the PCR was missed by both the RDT and blood film microscopy and thus went undiagnosed.