Evaluation of Diagnostic Accuracy of TB LAM Rapid Urine Antigen Screening Assay, GeneXpert and Smear Microscopy for TB and HIV Co-infected Population in the Guinea Savannah Zone of Nigeria

Abstract

Background: Report at the lunch of 1st Nigeria, National Strategic Plan for TB Control report opined that, at the current rate of transmission and development of Tuberculosis, over four million cases are forecasted to occur in Nigeria between 2015 and 2020 (WHO, 2015). Objectives: A study was conducted to examine diagnostic accuracy of GeneXpert, smear microscopy and TB LAM Rapid Urine Antigen Screening Assay for TB and HIV co-infected Population. Methods: 323 specimens from approximately 400 patients were enrolled using probability sampling technique. Selection intensity (CD4 count < 100, critical symptoms of TB and HIV) with stringent conditions was set to reduce eligible population for TB-LAM test. Differences between two groups was tested using t-test in SPSS-24 statistical package. Sensitivity, specificity, NPV and PPV were computed using Diagnostic or Screening Test Evaluation 1.0 using OpenEpi (version 2.3). Results: There were significant differences (P<0.05) among diagnostic accuracy for sensitivity, specificity, PPV, NPV and prevalence rate. The highest sensitivity was in GeneXpert (86.2%, 25/29) while TB-LAM the least sensitivity (57.5%, 46/80). EMS-AFB was significant (P<0.05) and more sensitive than Spot-AFB and TB-LAM. Specificity was significant (P=0.04) and slightly lower in the group tested with GeneXpert (90.8%) as compared to TB-LAM (100%), EMS-AFB (93.1%) and Spot-AFB (92.7%). The proportion of total study population with TB-LAM decreased linearly (23.2% - 7.4%) as the grades increases. Conclusion: This clearly suggest that TB-LAM might not be a robust testing for point of care diagnostics among TB-HIV co-infected Population using Zaria Metropolis of North Western, Nigeria.