Tuberculosis diagnosis in rural Namibia using gene Xpert MTB/RIF testing

Abstract

Namibia has the fourth highest tuberculosis (TB) incidence in the world. The Lifeline Clinic in rural Namibia is a charity aimed at helping the San, a population with a lifetime prevalence of TB of 25%. All TB diagnostic testing is performed at Gobabis hospital, 120km from the clinic. Gene Xpert MTB/RIF testing identifies Mycobacterium tuberculosis DNA and rifampicin resistance. The World Health Organisation (WHO) has endorsed its use in TB endemic countries. During the 2014/5 Namibian TB Drug Resistance Survey, when Gene Xpert was performed on all specimens, there was an increase in TB diagnoses at our clinic. Diagnoses declined after the trial stopped. This study was performed to determine how many extra TB diagnoses were made due to Gene Xpert. Between 1/7/14 and 9/6/15 Gene Xpert was performed on all sputum samples submitted to Gobabis hospital. Laboratory records of all samples were reviewed. Positive results were divided into those that would have been established by microscopy alone, and those only made due to Gene Xpert testing. There were 2067 samples. 1678 (81%) were negative. 354 TB diagnoses were made. 63% would have been made without use of Gene Xpert. 131 patients (37%) were diagnosed only because Gene Xpert was positive (microscopy in these patients was negative). These patients received prompter treatment due to this test, with an associated reduction in morbidity and mortality. This study confirms the benefit of Gene Xpert in establishing a TB diagnosis. The results are similar to previous WHO numbers. We recommend that its use and position in the TB diagnostic algorithm in developing countries is reviewed, and it is potentially utilised earlier and more frequently than currently.