Critical illness due to 2009 H1N1 influenza has been characterized by respiratory complications, including acute lung injury (ALI) or acute respiratory distress syndrome (ARDS), and associated with high mortality. We studied the severity, outcomes, and hospital charges of patients with ALI/ARDS secondary to pandemic influenza A infection compared with ALI and ARDS from other etiologies.
A retrospective review was conducted that included patients admitted to the Cleveland Clinic MICU with ALI/ARDS and confirmed influenza A infection, and all patients admitted with ALI/ARDS from any other etiology from September 2009 to March 2010. An itemized list of individual hospital charges was obtained for each patient from the hospital billing office and organized by billing code into a database. Continuous data that were normally distributed are presented as the mean±SD and were analyzed by the Student’s t test. The chi-square and Fisher exact tests were used to evaluate differences in proportions between patient subgroups. Data that were not normally distributed were compared with the Wilcoxon rank-sum test.
Forty-five patients were studied: 23 in the H1N1 group and 22 in the noninfluenza group. Mean±SD age was similar (44±13 and 51±17years, respectively, p=0.15). H1N1 patients had lower APACHE III scores (66±20 vs. 89±32, p=0.015) and had higher Pplat and PEEP on days 1, 3, and 14. Hospital and ICU length of stay and duration of mechanical ventilation were comparable. SOFA scores over the first 2weeks in the ICU indicate more severe organ failure in the noninfluenza group (p=0.017). Hospital mortality was significantly higher in the noninfluenza group (77 vs. 39%, p=0.016). The noninfluenza group tended to have higher overall charges, including significantly higher cost of blood products in the ICU.
ALI/ARDS secondary to pandemic influenza infection is associated with more severe respiratory compromise but has lower overall acuity and better survival rates than ALI/ARDS due to other causes. Higher absolute charges in the noninfluenza group are likely due to underlying comorbid medical conditions.
Keywords: ARDS, ALI, Influenza A, Novel influenza, Mechanical ventilation, Hospital cost