title: Testing Pooled Sputum with Xpert MTB/RIF for Diagnosis of Pulmonary Tuberculosis To Increase Affordability in Low-Income Countries.
abstract: Tuberculosis (TB) is a global public health problem, with the highest burden occurring in low-income countries. In these countries, the use of more sensitive diagnostics, such as Xpert MTB/RIF (Xpert), is still limited by costs. A cost-saving strategy to diagnose other diseases is to pool samples from various individuals and test them with single tests. The samples in positive pool samples are then retested individually to identify the patients with the disease. We assessed a pooled testing strategy to optimize the affordability of Xpert for the diagnosis of TB. Adults with presumptive TB attending hospitals or identified by canvassing of households in Abuja, Nigeria, were asked to provide sputum for individual and pooled (4 per pool) testing. The agreement of the results of testing of individual and pooled samples and costs were assessed. A total of 738 individuals submitted samples, with 115 (16%) being Mycobacterium tuberculosis positive. Valid Xpert results for individual and pooled samples were available for 718 specimens. Of these, testing of pooled samples detected 109 (96%) of 114 individual M. tuberculosis-positive samples, with the overall agreement being 99%. Xpert semiquantitative M. tuberculosis levels had a positive correlation with the smear grades, and the individual sample-positive/pooled sample-negative results were likely due to the M. tuberculosis concentration being below the detection limit. The strategy reduced cartridge costs by 31%. Savings were higher with samples from individuals recruited in the community, where the proportion of positive specimens was low. The results of testing of pooled samples had a high level of agreement with the results of testing of individual samples, and use of the pooled testing strategy reduced costs and has the potential to increase the affordability of Xpert in countries with limited resources.
authors.affiliation: Department of Public Health, Federal Capital Territory, Abuja, Nigeria.
authors.forename: Saddiq T
authors.initials: ST
authors.lastname: Abdurrahman
authors.affiliation: Liverpool School of Tropical Medicine, Liverpool, United Kingdom.
authors.forename: Omezikam
authors.initials: O
authors.lastname: Mbanaso
authors.affiliation: Zankli Medical Centre, Abuja, Nigeria Bingham University, Abuja, Nigeria.
authors.forename: Lovett
authors.initials: L
authors.lastname: Lawson
authors.affiliation: Zankli Medical Centre, Abuja, Nigeria.
authors.forename: Olanrewaju
authors.initials: O
authors.lastname: Oladimeji
authors.affiliation: Liverpool School of Tropical Medicine, Liverpool, United Kingdom.
authors.forename: Matthew
authors.initials: M
authors.lastname: Blakiston
authors.affiliation: Bingham University, Abuja, Nigeria Nigerian Centres for Disease Control, Abuja, Nigeria.
authors.forename: Joshua
authors.initials: J
authors.lastname: Obasanya
authors.affiliation: Liverpool School of Tropical Medicine, Liverpool, United Kingdom.
authors.forename: Russell
authors.initials: R
authors.lastname: Dacombe
authors.affiliation: Liverpool School of Tropical Medicine, Liverpool, United Kingdom.
authors.forename: Emily R
authors.initials: ER
authors.lastname: Adams
authors.affiliation: Zankli Medical Centre, Abuja, Nigeria.
authors.forename: Nnamdi
authors.initials: N
authors.lastname: Emenyonu
authors.affiliation: Stop TB Partnership Secretariat, Geneva, Switzerland.
authors.forename: Suvanand
authors.initials: S
authors.lastname: Sahu
authors.affiliation: Stop TB Partnership Secretariat, Geneva, Switzerland.
authors.forename: Jacob
authors.initials: J
authors.lastname: Creswell
authors.affiliation: Liverpool School of Tropical Medicine, Liverpool, United Kingdom luis.cuevas@lstmed.ac.uk.
authors.forename: Luis E
authors.initials: LE
authors.lastname: Cuevas
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001431:Bacteriological Techniques / Q000191:economics* / Q000379:methods*; D002648:Child; D003365:Costs and Cost Analysis; D003906:Developing Countries; D005260:Female; D017048:Health Care Costs; D006801:Humans; D008297:Male; D008875:Middle Aged; D025202:Molecular Diagnostic Techniques / Q000191:economics* / Q000379:methods*; D009169:Mycobacterium tuberculosis / Q000302:isolation & purification*; D009549:Nigeria; D012680:Sensitivity and Specificity; D013183:Sputum / Q000382:microbiology*; D014397:Tuberculosis, Pulmonary / Q000175:diagnosis*; D055815:Young Adult