ReviewSystematic review: Comparison of Xpert MTB/RIF, LAMP and SAT methods for the diagnosis of pulmonary tuberculosis
Introduction
The purpose of this review is to assess critically the current methods used to diagnose pulmonary tuberculosis (PTB), which is a contagious bacterial (Mycobacterium tuberculosis) infection that initially involves the lungs but may spread to other vital organs. It is important to diagnose PTB rapidly and accurately, as it is vital to treat patients immediately to minimize the risk of transmission of this airborne disease to other individuals in the local community. PTB is spread from person to person through the air for example when an infected individual coughs, sneezes or spits; a person only needs to inhale a few bacteria to become infected and is second only to HIV/AIDS as the greatest killer worldwide due to a single infectious agent. It has been estimated that in 2013, 9 million people contracted the disease of which 1.5 million died. More than 2 billion people are believed to be harboring M. tuberculosis but are asymptomatic [1]. Over 95% of TB deaths occur in low- and middle-income countries, and it is among the top 5 causes of death for women aged 15–44 and is a leading killer of HIV-positive people causing about 25% of all HIV-related deaths [2]. Much research has shown that early diagnosis would greatly improve efforts to prevent the spread of this devastating disease, whose symptoms include a severe cough, chest pains, night sweats, weight loss, coughing up of sputum and blood from deep within the lungs and others.
Thus, the aim of our review was to determine the diagnostic accuracies of the various methods available today to diagnose PTB, and to discuss their relative advantages and disadvantages.
Section snippets
Smear testing
Until recent years, sputum smear microscopy was the main method used for the diagnosis of PTB in low- and middle-income countries, where about 95% of TB cases and 98% of deaths due to PTB occur. Its advantage is that it is a simple, rapid and inexpensive technique, which is highly specific in areas with a very high prevalence of tuberculosis [1], [3]. It can also readily identify the most infectious patients and is widely applicable in various populations with different socio-economic levels [1]
Literature review and methodology
A systematic review of all published clinical studies of LAMP, SAT, and Xpert MTB/RIF for the diagnosis of PTB was carried out. We performed an electronic search of the PubMed, EMBASE, Cochrane, and Wanfang databases for previous studies of LAMP, SAT, and Xpert MTB/RIF published in English, with no limitation on publication year, using the following search terms: “loop-mediated isothermal amplification”, “tuberculosis”, “LAMP”, and “TB LAMP test; simultaneous amplification and testing method”,
HIV-positive/-negative subgroups
The pooled sensitivity and specificity for the HIV-positive subgroup were 79% (95%CI 0.71–0.86) and 99% (95%CI 0.97–0.99), and the I2 values were 72.9% and 64.4%, respectively, indicating moderate to significant heterogeneity. The pooled sensitivity and specificity for the HIV-negative subgroup were 72% (95%CI 0.62–0.80) and 99% (95%CI 0.97–0.99), respectively, and the I2 values were 49.6% and 64.5%, respectively, indicating moderate heterogeneity (Figure 9, Figure 10).
Smear-negative subgroups
Several research groups
Discussion
We conducted a systematic review of the literature to compare the diagnostic sensitivity and specificity of Xpert MTB/RIF, LAMP, and SAT for the diagnosis of PTB. The SAT method had the highest pooled sensitivity (96%), followed by LAMP (93%) and Xpert MTB/RIF (89%). The Xpert MTB/RIF test exhibited the highest pooled specificity (98%), followed by LAMP (94%) and SAT (88%). Therefore, the diagnostic sensitivity and specificity of the three methods were comparable. The I2 values for sensitivity
Conclusions
Technological advances in nucleic acid amplification have led to breakthroughs in the early detection of PTB compared to traditional sputum smear tests. The diagnostic sensitivity and specificity of three methods, namely LAMP, SAT, and Xpert MTB/RIF were similar. LAMP is highly sensitive for the diagnosis of smear-positive PTB. The cost effectiveness of LAMP and SAT make them particularly suitable for diagnosing PTB in developing countries.
Acknowledgments
This research was supported by a grant from China Ministry of Health (grant no. W2013RNA01).
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