title: The role of rapid testing and clinical decision in the diagnosis of human influenza A H1N1 infection.
abstract: OBJECTIVE
  To evaluate the role of the rapid influenza diagnostic test (RIDT) and clinical decision in the diagnosis of H1N1.
  
  
  METHODS
  In November 2009, 290 suspected influenza patients were examined for H1N1 during an outbreak in Riyadh, Saudi Arabia. Nasopharyngeal swabs were analyzed using Directigen EZ Flu A+B kit. Monoclonal anti-human influenza A/B and reverse transcription- polymerase chain reaction (RT-PCR) were used. Positive and negative controls were used in each run of specimens. Validity indices were calculated for RIDT and clinical diagnostic criteria.
  
  
  RESULTS
  The sensitivity and specificity of RIDT were 40.5% (95% confidence interval [CI]: 33.0-48.5), and 94.5% (95% CI: 88.6-97.6). The sensitivity of clinical decision was 66.3% (95% CI: 58.4-73.4), and the specificity was 65.4% (95% CI: 56.3-73.4). The sensitivity of clinical decision was higher in early presenters (79.2%; 95% CI: 57.3-92.1). The RIDT sensitivity was higher in younger patients (48.4%; 95% CI: 35.7-61.3). The positive predictive value (PPV) was 90.4% (95% CI: 80.7-95.7) for RIDT, and 71.1% (95% CI: 63.1-78.0) for clinical decision. The PPV for RIDT was greater for older (94.7%; 95% CI: 80.9-99.1) and late (90.7%; 95% CI: 76.9-97.0) presenters. The adjusted odds ratio for clinical decision was significant for cough, headache, and fatigue.
  
  
  CONCLUSIONS
  The RIDT can be useful in epidemics and high prevalence areas, whereas clinical decision, and RT-PCR complement the diagnosis of H1N1 in any setting.
authors.affiliation: Department of Family & Community Medicine (34), College of Medicine, King Saud University, PO Box 2925, Riyadh 11461, Kingdom of Saudi Arabia. Tel. +966 (11) 4670836. Fax. +966 (11) 4671967. E-mail: abinsaid@ksu.edu.sa.
authors.forename: Abdulaziz A
authors.initials: AA
authors.lastname: BinSaeed
authors.affiliation: Department of Family and Community Medicine, College of Medicine, King Saud University, Riyadh, Kingdom of Saudi Arabia.
authors.forename: Amna R
authors.initials: AR
authors.lastname: Siddiqui
authors.affiliation: Prince Sattam Bin Abdul Aziz Research Chair of Epidemiology and Public Health, College of Medicine, King Saud University, Riyadh, Kingdom of Saudi Arabia.
authors.forename: Ahmed M
authors.initials: AM
authors.lastname: Mandil
authors.affiliation: Department of Family and Community Medicine, College of Medicine, King Saud University, Riyadh, Kingdom of Saudi Arabia.
authors.forename: Armen A
authors.initials: AA
authors.lastname: Torchyan
authors.affiliation: Department of Family and Community Medicine, College of Medicine, King Saud University, Riyadh, Kingdom of Saudi Arabia.
authors.forename: Salwa A
authors.initials: SA
authors.lastname: Tayel
authors.affiliation: Department of Family and Community Medicine, College of Medicine, King Saud University, Riyadh, Kingdom of Saudi Arabia.
authors.forename: Shaffi A
authors.initials: SA
authors.lastname: Shaikh
authors.affiliation: Department of Pathology, College of Medicine, King Saud University, Riyadh, Kingdom of Saudi Arabia.
authors.forename: Hanan A
authors.initials: HA
authors.lastname: Habib
authors.affiliation: Department of Pathology, College of Medicine, King Saud University, Riyadh, Kingdom of Saudi Arabia.
authors.forename: Abdulaziz S
authors.initials: AS
authors.lastname: Al-Khattaf
mesh_terms: D000328:Adult; D003657:Decision Making; D005260:Female; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype / Q000302:isolation & purification*; D007251:Influenza, Human / Q000175:diagnosis* / Q000821:virology; D008297:Male; D012680:Sensitivity and Specificity; D055815:Young Adult