Diagnostic accuracy of serological rk-39 test for visceral Leishmaniasis: Systematic review and meta-analysis

Background: Visceral leishmaniasis (VL), or kala-azar, is a vector-borne tropical disease caused by a group of intracellular hemoflagellate protozoa belonging to the family of Trypanosomatide and the genus Leishmania. The disease is distributed around the world and transmitted via the bite of infected female Phlebotomine sandflies, and there is variation in the diagnostic accuracy. Therefore, this systematic review and meta-analysis aimed to determine the pooled global sensitivity and specificity of the rk-39 test and to evaluate if there is a difference between the different parts of the world. Methods: A systematic review and meta-analysis have been conducted on the diagnostic accuracy of dermoscopy. After setting eligibility criteria, literature was searched in four databases and one searching engine. Articles were screened, critically appraised, and extracted independently by two reviewers, and any disagreements were resolved with the involvement of a third person. The quality of the included studies had been assessed by the Quality Assessment of Diagnostic Accuracy Studies (QUADAS 2) tool. Pooled sensitivity and specificity were determined by bivariate random effect analysis. Heterogeneity was assessed by Higgins’s I2, and when it was present, mitigation was conducted by using sensitivity analysis. Result: A total of 409 studies were identified, and finally 18 articles were eligible for the review with a total sample size of 5, 253. The bivariate random effect meta-analysis of the 7 diagnostic accuracy studies showed a pooled sensitivity of 0.89 (0.76–0.95) and specificity of 0.86 (0.72–0.94). The +LR was 6.32 (95% CI: 2.85–14.02), the–LR was 0.13 (95% CI: 0.06–0.30), and the diagnostic odds ratio (DOR) was 47.8 (95% CI: 11.3–203.2). Abdel-Latif (2018) was both an outlier and influential for sensitivity, and Walter (2011) was both an outlier and influential for specificity, and removing them from sensitivity and specificity, respectively, was beneficial for reducing the heterogeneity. Conclusion: Rk-39 is found to have highly accurate measures in the diagnosis of visceral leishmaniasis. Both sensitivity and specificity were found to be highly accurate in the diagnosis of leishmaniasis, with a pooled sensitivity of 0.91 (0.88–0.93) and a pooled specificity of 0.89 (0.85–0.91). Ethical consideration: As we will use secondary data for the systematic review and meta-analysis, ethical concerns are not necessary. Author summary: Leishmaniasis is a vector-borne tropical disease distributed around the world and transmitted via the bite of infected sandflies. There are 3 main forms of the disease: visceral leishmaniasis, which is fatal if left untreated in over 95% of cases and is characterized by irregular bouts of fever, weight loss, enlargement of the spleen and liver, and anemia. The other form of the disease is cutaneous leishmaniasis, which causes skin lesions and life-long scars on exposed parts of the body. Whereas the third one, mucocutaneous leishmaniasis, leads to partial or total destruction of the mucous membranes of the nose, mouth and throat.