Evaluation of the diagnostic value of the tourniquet test in predicting severe dengue cases in a population from Belo Horizonte, State of Minas Gerais, Brazil

Introduction Dengue is prevalent in many tropical and sub-tropical regions. The clinical diagnosis of dengue is still complex, and not much data are available. This work aimed at assessing the diagnostic accuracy of the tourniquet test in patients with suspected dengue infection and its positivity in different classifications of this disease as reported to the Information System for Notifiable Disease in Belo Horizonte, State of Minas Gerais, Brazil between 2001 and 2006. Methods Cross-section analysis of the diagnostic accuracy of the tourniquet test for dengue, using IgM-anti-DENV ELISA as a gold standard. Results We selected 9,836 suspected cases, of which 41.1% were confirmed to be dengue. Classic dengue was present in 95.8%, dengue with complications in 2.5% and dengue hemorrhagic fever in 1.7%. The tourniquet test was positive in 16.9% of classic dengue cases, 61.7% of dengue cases with complications and 82.9% of cases of dengue hemorrhagic fever. The sensitivity and specificity of the tourniquet test were 19.1% and 86.4%, respectively. Conclusions A positive tourniquet test can be a valuable tool to support diagnosis of dengue where laboratory tests are not available. However, the absence of a positive test should not be read as the absence of infection. In addition, the tourniquet test was demonstrated to be an indicator of dengue severity.

引言：登革热（dengue）在众多热带及亚热带地区广泛流行。目前登革热的临床诊断仍较为复杂，且可用相关研究数据较为匮乏。本研究旨在评估束臂试验（tourniquet test）对疑似登革热感染患者的诊断准确性，以及该试验在不同分型登革热患者中的阳性率，研究数据取自2001年至2006年巴西米纳斯吉拉斯州贝洛奥里藏特市法定传染病信息系统（Information System for Notifiable Disease）上报的病例。
方法：本研究采用横断面分析方法，以抗登革病毒IgM酶联免疫吸附试验（IgM-anti-DENV ELISA）作为金标准，评估束臂试验用于登革热诊断的准确性。
结果：本研究共纳入9836例疑似病例，其中41.1%经确诊为登革热。确诊病例中，典型登革热占95.8%，伴并发症登革热占2.5%，登革出血热占1.7%。束臂试验阳性率在典型登革热病例中为16.9%，伴并发症登革热病例中为61.7%，登革出血热病例中为82.9%。束臂试验的灵敏度为19.1%，特异度为86.4%。
结论：在无法开展实验室检测的场景中，束臂试验阳性可作为辅助登革热诊断的有效工具。但需注意，束臂试验阴性结果不应直接判定为未发生登革热感染。此外，束臂试验阳性可作为登革热病情严重程度的潜在指示指标。