Comparison of Diagnostic Accuracy Between Traditional Microscopy and Rapid Diagnostic Tests for Malaria Detection

Thesis Abstract

Malaria remains a significant public health challenge in tropical and subtropical regions, necessitating accurate and timely diagnosis for effective disease management and control. Traditional microscopy has long been regarded as the gold standard for malaria diagnosis; however, it is labor-intensive, requires skilled personnel, and is susceptible to variability in interpretation. Rapid Diagnostic Tests (RDTs), on the other hand, offer a potentially faster and more deployable alternative but raise concerns regarding their diagnostic accuracy compared to microscopy. This study aims to evaluate and compare the diagnostic accuracy of traditional microscopy and RDTs for malaria detection in a high-burden setting, with specific objectives of determining sensitivity, specificity, positive predictive value, and negative predictive value of each method, and assessing their agreement using Kappa statistics. The research adopts a cross-sectional comparative design, conducted among 300 febrile patients presenting at peripheral health clinics in Accra, Ghana, selected through systematic random sampling. Blood samples collected from each participant will be analyzed concurrently using light microscopy following WHO standard procedures and two commercially available RDTs—CareStart Malaria HRP2 and SD Bioline Malaria Ag Pf/Pv. Data collection will utilize standardized laboratory protocols, with microscopy performed by experienced microscopists blinded to RDT results to prevent bias. The diagnostic performances will be evaluated through sensitivity, specificity, likelihood ratios, and predictive values, calculated using the gold-standard composite reference. Agreement between the two diagnostic modalities will be analyzed via Cohen’s Kappa coefficient, and the differences in diagnostic performance will be tested using McNemar's test for paired proportions. The study also will employ logistic regression to explore factors associated with false negatives and false positives, such as parasite density, age, and Plasmodium species. It is anticipated that the findings will demonstrate that RDTs have comparable sensitivity and specificity to microscopy in detecting Plasmodium falciparum infections, particularly at parasite densities exceeding 200 parasites per microliter, although some variability may exist with lower parasitemia or non-falciparum species. The expected contribution to knowledge includes providing comprehensive, context-specific evidence on the diagnostic reliability of RDTs versus microscopy, informing policy decisions on malaria diagnostic strategies, and identifying operational factors influencing test performance. The study concludes that while RDTs offer practical advantages in resource-limited settings, their limitations necessitate continued reliance on microscopy for confirmation, especially in cases of low parasitemia or mixed infections. Based on these findings, it recommends integrating RDTs into routine diagnosis where microscopy capacity is constrained, coupled with training programs to enhance microscopy quality assurance, and promoting the development of more sensitive and species-specific RDTs. This research ultimately aims to optimize malaria case management through evidence-based diagnostic approaches, thereby contributing to improved disease surveillance, treatment outcomes, and the broader goal of malaria control and eventual elimination in endemic regions.