Ishengoma DS,Shayo A, Mandara CI, Baraka V, Madebe RA, Ngatunga D,Kamugisha E,Gesase S,Ngadaya E, Mghamba J, Njau R, Mandike R,Mkude S, Mohamed A, Buzza J and Lemnge MM
Background: Since malaria rapid diagnostic tests (mRDTs) are widely used for parasitological diagnosis and targeting of treatment with effective antimalarials, this study assessed their performance for screening of patients to be enrolled in clinical trials and other studies, particularly in areas with progressively declining transmission.
Methods: Patients aged ≥ 6 months targeted for enrolment in clinical trials and studies of malaria parasite genomics were screened with mRDTs followed by microscopy. The performance of mRDTs was compared with microscopy as a gold standard, and factors affecting their accuracy were explored using multivariate logistic regression models.
Results: Of the 1,910 participants screened, 1,188 (62.1%) were positive by mRDTs and 1,019 (53.2%) by microscopy. Unadjusted sensitivity of mRDTs was >97% while the specificity was relatively lower (range; 64.9% to 88.7%). After adjusting for age, fever status, site and study type, the sensitivity of mRDTs was significantly higher (99.3%) in patients with parasite density ≥ 4000 asexual parasites/μl (OR=6.30, p=0.003). The specificity of mRDTs (adjusted for age, fever status, site and study type) was lower at all sites (p ≥ 0.525), except at Muleba and Ujiji where the specificity was significantly lower (p ≤ 0.007) due to high rates of false positive mRDT results.
Conclusion: High sensitivity indicate that mRDTs can be useful for initial screening to exclude majority of patients without malaria and save time and other resources which would be used for microscopy. Because of low specificity, all positive mRDT cases must be confirmed with microscopy to avoid enrolment of patients without malaria parasites.