Research Article: Impact of the Use of a Rapid Diagnostic Test for Visceral Leishmaniasis on Clinical Practice in Ethiopia: A Retrospective Study

Date Published: May 12, 2015

Publisher: Public Library of Science

Author(s): Ermias Diro, Lutgarde Lynen, Mahlet Assefa, Yegnasew Takele, Bewketu Mengesha, Emebet Adem, Rezika Mohammed, Robert Kimutai, Asrat Hailu, Marleen Boelaert, Johan van Griensven, Henk D. F. H. Schallig. http://doi.org/10.1371/journal.pntd.0003738

Abstract: BackgroundDiagnostic guidelines for Visceral Leishmaniasis (VL) in the East African region are complex. Patients meeting the VL clinical case definition should be tested by rK39 rapid diagnostic test (RDT) followed by the Direct Agglutination Test (DAT) or tissue aspiration if RDT-negative. Otherwise, RDT-positive patients should be started on VL treatment. We evaluated how this guideline is adhered to by assessing the routine clinical practice in a university hospital in North-West Ethiopia.MethodsRetrospective record analysis was done for all patients who had an rK39-RDT done at University of Gondar (UoG) Hospital between June 2012 and June 2013. We described the diagnostic work-up performed and the proportion initiated on VL treatment by test result.Results/FindingsFrom a total of 928 patients tested, 308 (33.2%) were rK39 RDT-positive. Spleen or bone marrow aspiration was done for 237 (77.2%) RDT-positive patients. Of these, 165 were confirmed parasitologically, yielding a positive predictive value of 69.6%. Only 126 (20.3%) of the 620 patients with a negative rK39 test underwent further testing by tissue aspiration, of which 22 (17.5%) were also parasitology positive. HIV test results were available for 570 (61.4%) patients and 36 (6.3%) were HIV-infected. Of the 187 parasitologically confirmed patients, 182 (97.3%) were started on VL treatment.Conclusions / DiscussionA negative rK39 test was often not followed by further testing and a positive rK39 test result was followed by tissue aspiration in three out of four cases. Further research is required to understand why the diagnostic work-up did not comply with the guidelines, including evaluating adherence to the VL clinical case definition and quality of rK39-RDT testing.

Partial Text: Visceral leishmaniasis (VL) is a vector borne, fatal disease caused by the protozoan parasite Leishmania. While Leishmania donovani is the etiologic agent in the East-African and Indian regions where transmission is anthroponotic, L infantum is the agent in the Mediterranean and Latin-American endemic regions, where transmission is zoonotic. It is an obligate intracellular organism that targets the reticuloendothelial system. The infection may initially remain dormant, manifesting in the presence of depressed cell mediated immunity at a later time. VL typically manifests with prolonged fever, weight loss, organomegaly and anemia [1].

Between June 2012 and June 2013, a total of 928 rK39 RDT tests were performed for clinical suspicion of VL. Most patients tested were male (89.2%), with a median age of 25 years (IQR 20–30). No data were available on the proportion of those 928 complying with the clinical case definition, because this was not routinely recorded. Out of 668 with a complete peripheral blood count result, 74 (11.1%) had a normal profile; 354 (53%) pancytopenia; 142 (21.3%) bicytopenia and 98 (14.7%) monocytopenia (Table 1). Leukopenia (white blood cell count <4500/μl) was found in 67.7% (457/675), anemia (hemoglobin <11g/dl) in 74.1% (501/676) and thrombocytopenia (platelet count < 150,000/μl) in 75.1% (503/670). In total, 308 (33.2%) had a positive rK39 RDT test result. Hematological abnormalities were more common in individuals testing rK39 positive (Table 1). RDTs have enabled an easy diagnosis of several diseases and have allowed to scale up treatment and control programs. However, there are concerns related to the high volume of tests used, the interpretation of results and quality assurance in the routine setting. This is one of the first studies evaluating VL testing practices by RDT in a routine clinical setting. While HIV test results and the subsequent actions for the rK39 negative patients were not available for a substantial proportion of individuals, linkage of the parasitologically confirmed VL cases to their treatment was good. The most striking finding was that the diagnostic work-up did not comply with the national guidelines [20]: a negative rK39 test was most of the time not followed by a second test for leishmanasis. On the other hand, a positive rK39 test result was followed by tissue aspiration in three out of four cases. The need for a parasitologically confirmed diagnosis in clinical trial protocols implemented at this clinical research center may partly explain the latter, but not the first scenario. Source: http://doi.org/10.1371/journal.pntd.0003738

 

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