Laboratory diagnostic systems used in the diagnosis of tuberculosis in Ethiopia: A systematic review

Abstract

Laboratories and laboratory tests are fundamental components of tuberculosis control programme; providing testing for diagnosis, surveillance and treatment monitoring at every level of health care system. This review is therefore, aimed at comparing and summarizing data on these laboratory systems used in the diagnosis of tuberculosis in Ethiopia. A systematic review of literature addressing the diagnosis of tuberculosis in Ethiopia was carried out. Literature search was done in MEDLINE and EMBASE for articles published from 2000 to 2013. We used the following search terms: Laboratory, tuberculosis, diagnosis and Ethiopia. Only studies addressing diagnostic systems of tuberculosis and English language publications were included. A total of 267 potential studies were identified by the search. Thirty-three studies qualified for the review. The reported diagnostic systems used to diagnose tuberculosis (TB) in Ethiopia included symptom screening, physical examination, chest X-ray, histology, histopathology, cytology, smear microscopy, tuberculin skin test (TST), QuantiFERON TB gold in tube and culture. Ten (30.3%) studies utilized culture as the reference standard and only one study employed polymerase chain reaction (PCR) as a standardized test. Most studies have used more than one diagnostic system. Four (12.5%) studies reported the use of sample processing methods (liquefaction and concentration of sputum using either sodium hypochlorite or sodium hydroxide followed by centrifugation) before actual tests, twenty seven (81.8%) studies used direct smear microscopy, three (9.4%) studies used TST and QuantiFERON-TB Gold In-Tube test (QFTGIT) together and two (6.3%) studies employed cytological techniques. Chest X-ray was employed in the majority of smear negative results with symptomatic patients suggestive of tuberculosis. The results of this review suggest that there is a need for revising the diagnostic systems. Most of the laboratory tests employed was based on direct smear microscopy which is insensitive and can only detect 36% of tuberculosis cases in Ethiopia. This may result in misdiagnosis of the disease and further transmission of the disease, especially in children and populations with high human immunodeficiency virus (HIV) co-infection. Therefore, there is need for laboratories to find a rapid and efficient method for TB diagnosis as a complement to the smear microscopy.