title: Clinical factors predictive of PCR positive in pandemic H1N1 2009 influenza virus infection.
abstract: OBJECTIVE
  Pandemic H1N1 2009 influenza virus (H1N1) has been spreading globally. Clinical features might be predictive and may be different among countries. Even though the PCR test is a confirmatory test for this viral infection, it is expensive and limited in most Thai health care facilities. We studied predictive factors of PCR positive in H1N1 suspected patients.
  
  
  METHODS
  Consecutive patients who had influenza-like illness less than seven days and had been tested for H1N1 by the real-time PCR method between May and July 2009 were enrolled. Clinical data was collected and compared between those who had positive and negative PCR tests.
  
  
  RESULTS
  There were 6494 patients had flu-like symptoms. Of those, 166 patients were done PCR test and 75 patients (45·18%) had positive PCR test. There were four predictors for positive PCR test including history of contact with confirmed H1N1 patients, headache, body temperature, and coryza with the adjusted odds ratio (95% confidence interval) of 2·84 (1·09-7·40), 6·25 (1·42-27·49), 1·69 (1·08-2·66), and 0·31 (0·12-0·79), respectively.
  
  
  CONCLUSIONS
  Clinical factors can be both suggestive and protective factors for H1N1 infection. These factors may be helpful in clinical practice to assess the possibility of the H1N1 infection in people who are at risk; particularly in resource-limited health care facilities.
authors.affiliation: Department of Emergency Medicine, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand.
authors.forename: Pariwat
authors.initials: P
authors.lastname: Phungoen
authors.forename: Kittisak
authors.initials: K
authors.lastname: Sawanyawisuth
authors.forename: Chulapan
authors.initials: C
authors.lastname: Engchanil
authors.forename: Sumitr
authors.initials: S
authors.lastname: Sutra
authors.forename: Dhanes
authors.initials: D
authors.lastname: Rangsrikajee
authors.forename: Viraphong
authors.initials: V
authors.lastname: Lulitanond
authors.forename: Jiraporn
authors.initials: J
authors.lastname: Srinakarin
authors.forename: Prakai
authors.initials: P
authors.lastname: Pithak
authors.forename: Janpen
authors.initials: J
authors.lastname: Bourpoern
authors.forename: Saisamon
authors.initials: S
authors.lastname: Phondongnok
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D053118:Influenza A Virus, H1N1 Subtype / Q000235:genetics / Q000302:isolation & purification*; D007251:Influenza, Human / Q000175:diagnosis / Q000453:epidemiology* / Q000821:virology*; D008297:Male; D008875:Middle Aged; D058873:Pandemics; D016133:Polymerase Chain Reaction; D011237:Predictive Value of Tests; D013785:Thailand / Q000453:epidemiology; D055815:Young Adult