Cost-effectiveness of GeneXpert Compared to Smear Microscopy for Diagnosis of Tuberculosis in Ethiopia

Abstract

Background Early diagnosis is one of the pillars of the TB (TB) control, and there are strong efforts to detect and treat cases in Ethiopia. Smear microscopy testing has been a routine test for the diagnosis of pulmonary TB in resource-constrained settings for a long time. Recently, many countries, including Ethiopia, are scaling up the use of GeneXpert without a precise evaluation of the cost and cost-effectiveness of this technology. Therefore, this study aimed to evaluate the cost-effectiveness of GeneXpert compared to smear microscopy tests for the diagnosis of TB patients in Ethiopia. Methods We develop a decision tree model using TreeAge Pro 2020 software. The model accounts for the prevalence and incidence of TB in the study area. The costs were estimated from the health providers' perspective in one year (in 2017/18). We applied an ingredients-based costing approach to identify, measure, and evaluate the smear microscopy cost and GeneXpert. We employed the 'proportion of cases detected' as an outcome measure of effectiveness. The incremental cost-effectiveness ratio (ICER) was calculated by dividing the changes in cost and change effectiveness. One way and probabilistic sensitivity analysis were done by varying different input parameters. All costs and ICER are reported in 2018 US$. Results The unit cost per test for GeneXpert and smear microscopy testing was US$12.9 and $3.1, respectively. The average cost of testing using GeneXpert was $113.0 and $3.3 for smear microscopy. The cost of the cartridge ($10.7) was the primary (83%) parameter influencing the overall cost of GeneXpert, while it was the cost of reagent and consumables $1.28 (41%) for the smear microscopy. The ICER for GeneXpert strategy was $729.8 per new TB cases detected compared to smear microscopy. The sensitivity analysis indicates that TB prevalence was the most influential parameter on the ICER. Conclusion The present study indicates that testing all individuals with suspected TB using GeneXpert is a very cost-effective strategy compared to smear microscopy, and therefore, it can be part of the routine diagnostic testing strategy in Ethiopia.

Tween 80 Improves the Acid-Fast Bacilli Quantification in the Magnetic Nanoparticle-Based Colorimetric Biosensing Assay (NCBA)

“…In addition, NCBA shows numerous advantages compared to SSM: (a) the ability of NCBA to form GMNP-AFB complexes and concentrate AFB [ 20 ], through the glycan-glycoprotein interaction between the GMNP surface and the mycobacterial cell wall [ 21 ]; (b) after cell enrichment with GMNP, disaggregation of complexes with Tween 80 improves the microscopic quantification of AFB; (c) a larger volume of sample analyzed (by concentrating it with GMNP) in the same proportion of examined area may facilitate the ability to obtain higher AFB counts [ 22 ]; (d) the AFB detected and captured by GMNP, followed by ZN staining of concentrated aliquots, allows easy identification by colorimetry, which may increase the possibility to identify bacilli from paucibacillary cases [ 21 ]; (e) it is a fast method, since the complete processing can be obtained in 30–40 min from sample acquisition to final diagnostic result; (f) it is a direct and quantitative detection technique where bacilli can be viewed and counted through a microscope; (g) it is a low-cost method: one test, including materials, labor and infrastructure overhead, costs approximately USD 3.20 for NCBA and USD 4.20 with Tween 80, compared to other methods, such as culture (USD 16.50) [ 67 ], and molecular tests, such as GeneXpert (USD 12.90) [ 68 ]; (h) it does not require complex infrastructure, allowing its applicability in settings where TB is a burden, but resources are limited; and (i) offers bio-safety, since the NCBA-GMNP assay does not require centrifugation to concentrate AFB, thus reducing the generation of infectious aerosols, and the addition of Tween 80 may also reduce infectivity, due to the loss of virulence factors from the mycobacterial cell wall [ 60 , 61 , 64 ].…”

Aptamer-Based Diagnostic Systems for the Rapid Screening of TB at the Point-of-Care

“…Despite the necessity of diagnostic approaches such as GeneXpert in countries with high TB incidences, the cost is considered exorbitant. The unit cost of a single GeneXpert test in the USA was about USD 12.9 in 2018 [78]. However, based on 2018 estimates, this technology is too costly for developing countries as the average testing and cartridge costs were reported to be USD 113 and 10.7, respectively [78].…”

“…The unit cost of a single GeneXpert test in the USA was about USD 12.9 in 2018 [78]. However, based on 2018 estimates, this technology is too costly for developing countries as the average testing and cartridge costs were reported to be USD 113 and 10.7, respectively [78]. Nevertheless, over 150 civil society organisations across the world have joined 'The Time for 5 US$ Coalition', which aims to reduce the cartridge costs to USD 5 [79].…”