title: Comparison of characteristics of outpatients with 2009 H1N1 pandemic and seasonal influenza.
abstract: BACKGROUND
  The latest influenza pandemic intensified the interest in this infection.
  
  
  OBJECTIVE
  We aimed to compare the characteristics of outpatients with seasonal and pandemic influenza.
  
  
  METHODS
  We retrospectively reviewed data regarding outpatients who sought medical advice from a network of physicians performing house-call visits at the area of Attica, Greece, and who underwent a direct influenza test during the period of seasonal influenza (1/1/2009-1/5/2009) and 2009 H1N1 pandemic influenza period (17/5/2009-15/4/2010).
  
  
  RESULTS
  A total of 195 and 1317 patients had a direct influenza test during the seasonal and pandemic influenza period, respectively; 50.7% and 32% of these patients had a positive test result for influenza, respectively. Viral culture or polymerase chain reaction (PCR) were not implemented. Patients found positive for influenza during the pandemic period, compared with those evaluated during the seasonal period, were younger (mean age ± SD: 33 ± 17.2 vs. 38.2 ± 19.2, p = 0.008), more likely to have no comorbidity (62.9% vs. 45.5%, p = 0.002), had milder clinical manifestations, and were treated with more antibiotics (38.3% vs. 9.9%, p < 0.001). However, patients found positive during the seasonal period were treated with more antivirals (oseltamivir: 69.1% vs. 85.7%, p = 0.006). No difference was observed regarding the need for immediate hospitalisation. These findings were consistent in the complementary analysis involving patients tested for influenza during the compared periods.
  
  
  CONCLUSIONS
  Despite the methodological limitations, our findings suggest that patients with pandemic influenza were younger, had milder clinical manifestations and were less likely to have any kind of comorbidity compared with patients with seasonal influenza.
authors.affiliation: SOS Doctors, Athens, Greece.
authors.forename: G
authors.initials: G
authors.lastname: Theocharis
authors.forename: E K
authors.initials: EK
authors.lastname: Vouloumanou
authors.forename: S G
authors.initials: SG
authors.lastname: Barbas
authors.forename: T
authors.initials: T
authors.lastname: Spiropoulos
authors.forename: P I
authors.initials: PI
authors.lastname: Rafailidis
authors.forename: M E
authors.initials: ME
authors.lastname: Falagas
mesh_terms: D000293:Adolescent; D000328:Adult; D000553:Ambulatory Care / Q000706:statistics & numerical data*; D002648:Child; D002675:Child, Preschool; D005260:Female; D006115:Greece / Q000453:epidemiology; D006801:Humans; D007223:Infant; D053118:Influenza A Virus, H1N1 Subtype; D007251:Influenza, Human / Q000175:diagnosis / Q000188:drug therapy / Q000453:epidemiology*; D008297:Male; D008875:Middle Aged; D058873:Pandemics / Q000706:statistics & numerical data*; D010342:Patient Acceptance of Health Care / Q000706:statistics & numerical data; D012189:Retrospective Studies; D012621:Seasons; D055815:Young Adult