Clinical performance of an automated reader in interpreting malaria rapid diagnostic tests in Tanzania

Abstract

Background: Parasitological confirmation of malaria is now recommended in all febrile patients by the World Health Organization (WHO) to reduce inappropriate use of anti-malarial drugs. Widespread implementation of rapid diagnostic tests (RDTs) is regarded as an effective strategy to achieve this goal. However, the quality of diagnosis provided by RDTs in remote rural dispensaries and health centres is not ideal. Feasible RDT quality control programmes in these settings are challenging. Collection of information regarding diagnostic events is also very deficient in low-resource countries.

Methods: A prospective cohort of consecutive patients aged more than one year from both genders, seeking routine care for febrile episodes at dispensaries located in the Bagamoyo district of Tanzania, were enrolled into the study after signing an informed consent form. Blood samples were taken for thick blood smear (TBS) microscopic examination and malaria RDT (SD Bioline Malaria Antigen Pf/Pan™ (SD RDT)). RDT results were interpreted by both visual interpretation and Deki Reader™ device. Results of visual interpretation were used for case management purposes. Microscopy was considered the "gold standard test" to assess the sensitivity and specificity of the Deki Reader interpretation and to compare it to visual interpretation.

Results: In total, 1,346 febrile subjects were included in the final analysis. The SD RDT, when used in conjunction with the Deki Reader and upon visual interpretation, had sensitivities of 95.3% (95% CI, 90.6-97.7) and 94.7% (95% CI, 89.8-97.3) respectively, and specificities of 94.6% (95% CI, 93.5-96.1) and 95.6% (95% CI, 94.2-96.6), respectively to gold standard. There was a high percentage of overall agreement between the two methods of interpretation.

Conclusion: The sensitivity and specificity of the Deki Reader in interpretation of SD RDTs were comparable to previous reports and showed high agreement to visual interpretation (>98%). The results of the study reflect the situation in real practice and show good performance characteristics of Deki Reader on interpreting malaria RDTs in the hands of local laboratory technicians. They also suggest that a system like this could provide great benefits to the health care system. Further studies to look at ease of use by community health workers, and cost benefit of the system are warranted.

Figure 1

Deki Reader^TM device.

Figure 2

Patient Flowchart for Deki Reader RDT result. *Subjects were enrolled as part of a pilot run of the study, but excluded from the final analysis as planned. Intent-to-Assay: Included all enrolled subjects who met all inclusion and exclusion requirements and whose test was inserted within the 30-minute window, as per protocol.