title: Delay in diagnosis of influenza A (H1N1)pdm09 virus infection in critically ill patients and impact on clinical outcome.
abstract: BACKGROUND
  Patients infected with influenza A (H1N1)pdm09 virus requiring admission to the ICU remain an important source of mortality during the influenza season. The objective of the study was to assess the impact of a delay in diagnosis of community-acquired influenza A (H1N1)pdm09 virus infection on clinical outcome in critically ill patients admitted to the ICU.
  
  
  METHODS
  A prospective multicenter observational cohort study was based on data from the GETGAG/SEMICYUC registry (2009-2015) collected by 148 Spanish ICUs. All patients admitted to the ICU in which diagnosis of influenza A (H1N1)pdm09 virus infection had been established within the first week of hospitalization were included. Patients were classified into two groups according to the time at which the diagnosis was made: early (within the first 2 days of hospital admission) and late (between the 3rd and 7th day of hospital admission). Factors associated with a delay in diagnosis were assessed by logistic regression analysis.
  
  
  RESULTS
  In 2059 ICU patients diagnosed with influenza A (H1N1)pdm09 virus infection within the first 7 days of hospitalization, the diagnosis was established early in 1314 (63.8 %) patients and late in the remaining 745 (36.2 %). Independent variables related to a late diagnosis were: age (odds ratio (OR) = 1.02, 95 % confidence interval (CI) 1.01-1.03, P < 0.001); first seasonal period (2009-2012) (OR = 2.08, 95 % CI 1.64-2.63, P < 0.001); days of hospital stay before ICU admission (OR = 1.26, 95 % CI 1.17-1.35, P < 0.001); mechanical ventilation (OR = 1.58, 95 % CI 1.17-2.13, P = 0.002); and continuous venovenous hemofiltration (OR = 1.54, 95 % CI 1.08-2.18, P = 0.016). The intra-ICU mortality was significantly higher among patients with late diagnosis as compared with early diagnosis (26.9 % vs 17.1 %, P < 0.001). Diagnostic delay was one independent risk factor for mortality (OR = 1.36, 95 % CI 1.03-1.81, P < 0.001).
  
  
  CONCLUSIONS
  Late diagnosis of community-acquired influenza A (H1N1)pdm09 virus infection is associated with a delay in ICU admission, greater possibilities of respiratory and renal failure, and higher mortality rate. Delay in diagnosis of flu is an independent variable related to death.
authors: Service of Intensive Care Medicine, Hospital del Mar, Passeig Marítim 25-29, E-08003, Barcelona, Spain. FAlvarez@parcdesalutmar.cat.|Research Group in Critical Disorders (GREPAC), Institut Hospital del Mar d'Investigacions Mèdiques (IMIM), Barcelona, Spain. FAlvarez@parcdesalutmar.cat.|Universitat Autónoma de Barcelona, Barcelona, Spain. FAlvarez@parcdesalutmar.cat.
authors: Francisco
authors: F
authors: Álvarez-Lerma
authors: Service of Intensive Care Medicine, Hospital del Mar, Passeig Marítim 25-29, E-08003, Barcelona, Spain.|Research Group in Critical Disorders (GREPAC), Institut Hospital del Mar d'Investigacions Mèdiques (IMIM), Barcelona, Spain.
authors: Judith
authors: J
authors: Marín-Corral
authors: Service of Intensive Care Medicine, Hospital del Mar, Passeig Marítim 25-29, E-08003, Barcelona, Spain.
authors: Clara
authors: C
authors: Vila
authors: Service of Intensive Care Medicine, Hospital del Mar, Passeig Marítim 25-29, E-08003, Barcelona, Spain.|Research Group in Critical Disorders (GREPAC), Institut Hospital del Mar d'Investigacions Mèdiques (IMIM), Barcelona, Spain.|CIBER de Enfermedades Respiratorias (CIBERES), Madrid, Spain.|Universitat Pompeu Fabra, Barcelona, Spain.
authors: Joan Ramón
authors: JR
authors: Masclans
authors: Service of Intensive Care Medicine, Hospital Universitari Mútua de Terrassa, Terrassa, Barcelona, Spain.
authors: Francisco Javier
authors: FJ
authors: González de Molina
authors: Service of Intensive Care Medicine, St James Hospital, Dublin, Ireland.
authors: Ignacio
authors: I
authors: Martín Loeches
authors: Service of Intensive Care Medicine, Hospital General de Catalunya, Sant Cugat del Vallés, Barcelona, Spain.
authors: Sandra
authors: S
authors: Barbadillo
authors: CIBER de Enfermedades Respiratorias (CIBERES), Madrid, Spain.|Service of Intensive Care Medicine, Hospital Universitari Joan XXIII, IISPV-URV, Tarragona, Spain.
authors: Alejandro
authors: A
authors: Rodríguez
mesh_terms: D000328:Adult; D000368:Aged; D016009:Chi-Square Distribution; D016638:Critical Illness / Q000453:epidemiology; D057210:Delayed Diagnosis; D005260:Female; D017052:Hospital Mortality; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype / Q000472:pathogenicity; D007251:Influenza, Human / Q000175:diagnosis*; D007362:Intensive Care Units / Q000458:organization & administration / Q000706:statistics & numerical data; D007902:Length of Stay; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D011446:Prospective Studies; D012307:Risk Factors; D013030:Spain / Q000453:epidemiology; D018709:Statistics, Nonparametric
keywords: Critically ill; Early diagnosis; ICU; Influenza A (H1N1)pdm09 virus infection; Late diagnosis; Mortality; Outcome