title: Accuracy of clinical criteria and an immunochromatographic strip test for dengue diagnosis in a DENV-4 epidemic.
abstract: BACKGROUND
  Early diagnosis of dengue infection is important for decision-making and timely implementation of therapeutic measures. Although rapid NS1 assays have been used for dengue diagnosis since 2008, their performance in DENV-4 cases has not yet been fully assessed.
  
  
  METHODS
  We evaluated the accuracy of NS1 Bioeasy™ immunochromatographic strip test and of three clinical criteria for dengue diagnosis. Patients presenting at an emergency care center within 72 h of an acute febrile illness during the 2013 DENV-4 epidemic in Rio de Janeiro were consecutively enrolled for clinical and laboratory evaluation. We classified patients as suspected dengue or not according to three clinical criteria: WHO 2009, WHO 1997, and INI-FIOCRUZ. Dengue diagnosis was defined by RNA detection using RT-PCR and the negative cases were negative for all dengue serotypes and also Platelia™ NS1 ELISA. We obtained accuracy indices for NS1 Bioeasy™ alone and in combination with the clinical criteria.
  
  
  RESULTS
  RT-PCR for DENV-4 was positive in 148 out of 325 patients. Positive likelihood ratio, sensitivity, and specificity of NS1 Bioeasy™ with WHO 2009, WHO 1997, and INI-FIOCRUZ criteria were 22.6 (95% CI 7.2-70.6), 40.6% (95% CI 32.3-49.3), and 98.2% (95% CI 94.9-99.6); 18.3 (95% CI 6.8-49.2), 44.2 (95% CI 35.8-52.9), 97.6 (95% CI 94.0-99.3); 26.2 (95% CI 6.5-106.5), 29.7 (95% CI 22.4-37.8), 98.9 (95% CI 96.0-99.9), respectively. WHO 1997 clinical criteria presented high sensitivity to rule out disease, but extremely low specificity. INI-FIOCRUZ had moderate sensitivity and specificity, and could target a group to a more specific test.
  
  
  CONCLUSIONS
  Although the large rates of false negative results using NS1 Bioeasy™ rapid test advise against its use for triaging (rule out) purposes in DENV-4 epidemics, it could be used as a confirmatory tool in a bedside algorithm.
authors.affiliation: Laboratory of Clinical Epidemiology, Evandro Chagas National Institute of Infectious Diseases, Oswaldo Cruz Foundation, Rio de Janeiro, Brazil. sibellebuonora@gmail.com.
authors.forename: Sibelle Nogueira
authors.initials: SN
authors.lastname: Buonora
authors.affiliation: Laboratory of Clinical Epidemiology, Evandro Chagas National Institute of Infectious Diseases, Oswaldo Cruz Foundation, Rio de Janeiro, Brazil. sonialambert@gmail.com.
authors.forename: Sonia Regina Lambert
authors.initials: SR
authors.lastname: Passos
authors.affiliation: National School of Public Health, Oswaldo Cruz Foundation, Rio de Janeiro, Brazil. cleber.carmo@gmail.com.
authors.forename: Cleber Nascimento
authors.initials: CN
authors.lastname: do Carmo
authors.affiliation: Laboratory of Clinical Epidemiology, Evandro Chagas National Institute of Infectious Diseases, Oswaldo Cruz Foundation, Rio de Janeiro, Brazil. nandamq@hotmail.com.
authors.forename: Fernanda Moisés
authors.initials: FM
authors.lastname: Quintela
authors.affiliation: Laboratory of Clinical Epidemiology, Evandro Chagas National Institute of Infectious Diseases, Oswaldo Cruz Foundation, Rio de Janeiro, Brazil. diana_nro@hotmail.com.
authors.forename: Diana Neves Rodrigues
authors.initials: DN
authors.lastname: de Oliveira
authors.affiliation: Flavivirus Laboratory, Oswaldo Cruz Institute, Oswaldo Cruz Foundation, Rio de Janeiro, Brazil. flaviab@ioc.fiocruz.br.
authors.forename: Flavia Barreto
authors.initials: FB
authors.lastname: dos Santos
authors.affiliation: Laboratory of Clinical Epidemiology, Evandro Chagas National Institute of Infectious Diseases, Oswaldo Cruz Foundation, Rio de Janeiro, Brazil. yarahahr@gmail.com.
authors.forename: Yara Hahr Marques
authors.initials: YH
authors.lastname: Hökerberg
authors.affiliation: Flavivirus Laboratory, Oswaldo Cruz Institute, Oswaldo Cruz Foundation, Rio de Janeiro, Brazil. rita@ioc.fiocruz.br.
authors.forename: Rita Maria Ribeiro
authors.initials: RM
authors.lastname: Nogueira
authors.affiliation: Germano Sinval Faria Teaching Primary Care Center, National School of Public Health, Oswaldo Cruz Foundation, Rio de Janeiro, Brazil. regina.daumas@gmail.com.
authors.forename: Regina Paiva
authors.initials: RP
authors.lastname: Daumas
mesh_terms: D000328:Adult; D001938:Brazil / Q000453:epidemiology; D003715:Dengue / Q000175:diagnosis* / Q000453:epidemiology / Q000821:virology; D003716:Dengue Virus / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D042241:Early Diagnosis; D004797:Enzyme-Linked Immunosorbent Assay; D058872:Epidemics; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D019095:Point-of-Care Systems; D012367:RNA, Viral / Q000032:analysis; D011933:Reagent Kits, Diagnostic; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012680:Sensitivity and Specificity; D065288:Serogroup; D017361:Viral Nonstructural Proteins / Q000032:analysis / Q000276:immunology
chemical_list: D012367:RNA, Viral; D011933:Reagent Kits, Diagnostic; D017361:Viral Nonstructural Proteins
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