513. SOFA Score Variability by Influenza Season and ICU Type
Session: Poster Abstract Session: Influenza and other Respiratory Viral Infections Epidemiology Studies
Friday, October 21, 2011
Room: Poster Hall B1
  • IDSA Poster - Bayles & Lawrence.pdf (364.5 kB)
  • Background: Severe respiratory events, such as pandemic influenza, have the potential to exert significant demands on hospital resources. The Sequential Organ Failure Assessment (SOFA) score has been suggested as a triage tool for the allocation of scarce critical care resources; however, little is known about the impact such triage would have on existing patients in different intensive care units (ICU) during times of variable influenza activity.

    Methods: A retrospective cohort study was conducted on all adult patients admitted to medical (MICU) and surgical (SICU) ICUs at a large tertiary care medical center in St. Louis, Missouri during four separate 30-day periods: (1) no influenza activity [May-June 2008], peaks of influenza activity during (2) a severe seasonal epidemic [January-February 2008], (3) a mild seasonal epidemic [February-March 2009], and 4) H1N1 pandemic [October 2009]. Clinical data, including modified SOFA (mSOFA) scores, were compared between ICU groups and across periods using Chi-Square, Fisher’s, and Mann-Whitney U tests where appropriate.

    Results: 2,728 patients were included, of which 36 (1.3%) had laboratory-confirmed influenza. Influenza incidence was highest in the MICU during period 2 (5.2%; p<.001 between ICUs and between periods). There were no differences in ventilator use by ICU type (24.8% vs. 23.3%) or between periods (22.3% – 25.9%). Median initial and 7-day maximum mSOFA scores were lower in the MICU (3 and 3 respectively) compared to the SICU (4 and 5 respectively; p<.001) across all time periods. The proportion of patients with a mSOFA score ≥11 was lower in the MICU compared to the SICU (2.2% vs. 3.8% respectively; p=.01). Median daily mSOFA (3.5) and maximum mSOFA ≥11 (3.4%) were highest in period 4 across both ICUs (p<.001).

    Conclusion: Even during periods of recent peak activity, influenza has had a modest impact on ICU resource utilization. Higher mSOFA scores were associated with the SICU and with peak pandemic (H1N1) 2009 influenza activity. If SOFA score-based triage protocols are implemented during a future severe pandemic, pre-existing SICU patients may be disproportionately affected.  In that setting, cancellation of elective surgeries to reduce SICU populations may be a critical mitigation strategy.

    Subject Category: N. Hospital-acquired and surgical infections, infection control, and health outcomes including general public health and health services research

    Brett R. Bayles, M.P.H., Saint Louis University School of Public Health, St. Louis, MO and Steven J. Lawrence, M.D., M.Sc., Washington University, St. Louis, MO


    B. R. Bayles, None

    S. J. Lawrence, None

    Findings in the abstracts are embargoed until 12:01 a.m. EST Thursday, Oct. 20 with the exception of research findings presented at IDSA press conferences.