Low sensitivity of the tourniquet test for differential diagnosis of dengue: an analysis of 28,000 trials in patients.
BACKGROUND
The aim of this study was to evaluate the utility of the tourniquet test (TT) for dengue diagnosing. To our knowledge, no previous study with such a large sample, of this duration, with as many laboratory methods referenced, or relating the results of the TT to the 2009 WHO classification of severity has been conducted thus far.


METHODS
In this study, we analyzed the records of 119,589 suspected dengue cases in a Brazilian city, with 30,670 confirmed cases. The Cohen's Kappa test was applied to evaluate the degree of agreement between the tests, and the sensitivity and specificity was calculated for the TT.


RESULTS
Twenty-eight thousand six hundred thirty-five TT were performed. No association between the outcome of the TT and greater severity of infection, according to the 2009 guideline, was observed (P = 0.28); furthermore, relevant agreement with the final diagnosis (κ = 0.01; 95 % CI = 0.00 to 0.02) or individually with the IgM enzyme-linked immunoassay was not observed (κ = 0.05; 95 % CI = 0.04 to 0.06), and was even lower with PCR (κ = 0.27; 95 % CI = 0.06 to 0.49). Most importance of the TT was shown in relation to specificity (88.9 %; 95 % CI = 0.88 to 0.89) and negative predictive value (70.3 %; CI 95 % = 0.70 to 0.71).


CONCLUSIONS
TT was more effective in detecting cases that were truly negative than positive. These results suggest that the TT should not be used as diagnosis of dengue.
Faculdade de Medicina, União das Faculdades dos Grandes Lagos, São José do Rio Preto, São Paulo, Brazil.
Nathália Barbosa
NB
Furlan
Faculdade de Medicina, União das Faculdades dos Grandes Lagos, São José do Rio Preto, São Paulo, Brazil.
Caroline
C
Tukasan
Faculdade de Medicina, União das Faculdades dos Grandes Lagos, São José do Rio Preto, São Paulo, Brazil.|Laboratório de Pesquisas em Virologia, Faculdade de Medicina de São José do Rio Preto, São Paulo, Brazil.
Cássia Fernanda
CF
Estofolete
Laboratório de Pesquisas em Virologia, Faculdade de Medicina de São José do Rio Preto, São Paulo, Brazil.
Maurício Lacerda
ML
Nogueira
Faculdade de Medicina, União das Faculdades dos Grandes Lagos, São José do Rio Preto, São Paulo, Brazil. natalss@gmail.com.|Laboratório de Pesquisas em Virologia, Faculdade de Medicina de São José do Rio Preto, São Paulo, Brazil. natalss@gmail.com.|Laboratório de Modelagens Matemática e Estatística em Medicina, União das Faculdades dos Grandes Lagos, São José do Rio Preto, São Paulo, Brazil. natalss@gmail.com.|Laboratório de Modelagens Matemática e Estatística em Medicina, Faculdade de Medicina, União das Faculdades dos Grandes Lagos, Rua Dr. Eduardo Nielsem, 960 Jardim Novo Aeroporto, São Jose do Rio Preto, São Paulo, CEP 15030-070, Brazil. natalss@gmail.com.
Natal Santos
NS
da Silva
D000293:Adolescent; D000328:Adult; D001938:Brazil; D002648:Child; D002675:Child, Preschool; D003715:Dengue / Q000175:diagnosis* / Q000276:immunology; D003716:Dengue Virus / Q000235:genetics / Q000276:immunology; D003937:Diagnosis, Differential; D022062:Electrophysiologic Techniques, Cardiac; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D007124:Immunoenzyme Techniques; D007075:Immunoglobulin M / Q000276:immunology; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D016133:Polymerase Chain Reaction; D012680:Sensitivity and Specificity; D014111:Tourniquets; D055815:Young Adult
D007075:Immunoglobulin M
Dengue; Diagnostic test for dengue; Tourniquet test