Assessment of Diagnostic Performance of Abbott Real Time PCR for the Detection of Smear Negative Pulmonary Tuberculosis at Ethiopian Public Health Institute, Addis Ababa Ethiopia
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Date
2018-11
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Addis Ababa University
Abstract
Background: In 2016, an estimated 10.4 million people developed TB and of these more than 1.6million died from the disease, 374,000 (22%) of whom were HIV-positive. In most of the highburden of tuberculosis but resource poor countries, microscopy method issued in which acidfastbacilli are detected in smear using a light microscope. However, smear microscopy is not soreliable. As of other most advanced tests, molecular techniques still not implemented indeveloping countries including Ethiopia. To improve MTB case detection rate, there is a need tointroduce and implement rapid batch testing molecular methods in Ethiopia.
Objective: The objective of this study was to assess the performance characteristics of Abbott realtime for the diagnosis smear negative MTB
Methods: Both prospective and retrospective cross-sectional survey was carried out to enroll 127study participants’ records along with left over sputum specimens in Addis Ababa, EPHI nationalTB/HIV laboratories from March to May 2018. Performance characteristics including sensitivity,specificity and predictive values was calculated by using SPSS version 23 with 95% CI. For allstatistical significance tests, the cut-off point was 0.05 and p < 0.05 considered as statisticallysignificant association with testing performance.
Results: Diagnostic sensitivity of Abbott real time for the diagnosis of smear negative was 82.9%and specificity exhibited 89.1%. Drug susceptibility testing demonstrated diagnostic specificity of87.5% and 100% for INH and RIF respectively. Abbott real time performance significantly andnegatively associated with month of treatment [Adjusted OR (95%CI) = 0.01 (0.00. 0.41)] for 1stto 6th month, 0.005 (0.00, 0.20) for 7th to 12th months and 0.001 (0.00, 0.90) for the clients ontreatment for more than a year
Conclusions: The diagnostic sensitivity of the method for identification of MTB and drug resistancesensitivityand specificity similar with the previous similar studies. The method exhibited lowerspecificity for the diagnosis smear negative MTB cases. The finding also revealed the specificity ofAbbott real time the lowest as of other molecular methods for the diagnosis of smear negative MTBcases who are on MTB treatment. Therefore, we strongly recommend not to use the method for allfollow-up MTB cases except zero month and further investigation should be continued to explainexhaustively the effect of explanatory variables on Abbott MTB performance.
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Keywords
Abbott real time PCR, MTB, Sensitivity, Specificity