523. Biosurveillance for Influenza-Like Illness in Veterans Affairs Healthcare Facilities during the 2009 Novel H1N1 Outbreak
Session: Poster Session: Hospital-acquired and Transplant Infections
Friday, October 30, 2009: 12:00 AM
Room: Poster Hall A
Background: During the H1N1 influenza outbreak of 2009 we analyzed influenza-like illness (ILI) coded outpatient visit data across the Veterans Affairs (VA) healthcare system to determine influenza activity and trends within the VA.
Methods: VA’s Electronic Surveillance System for the Early Notification of Community-Based Epidemics (ESSENCE) detects outpatient and emergency room visits with ILI ICD-9 codes and provides an alerting mechanism when numbers exceed expected values. We performed a retrospective analysis of all VA ILI outpatient data from April-May 2009. Influenza-specific ICD-9 coded visits (487.0, 487.1, 487.8) underwent chart review for additional data collection.
Results: From April 19-May 16, 2009, a total of 36,086 patients with ILI were seen and 1.8% of those had influenza-specific ICD-9 codes. During the peak week of H1N1 activity (April 26-May 2), 10,934 patients were seen for an ILI representing 1.1% of all VA visits, triggering high-level alerts mirroring nationally reported ILI surveillance. During that week, the top three ILI codes were 38% upper respiratory infection (465.9), 33% cough (786.2), and 20% acute bronchitis (466.0). Influenza-specific ICD-9 codes accounted for 307 (2.8%) visits. A representative sample of 133 cases were reviewed and indicated that 93% were symptomatic, 36% had rapid flu testing, and 26% were prescribed antiviral therapy. Of those tested, 22% (11/49) were positive for influenza with 70% identified as influenza A and 30% as influenza B.
Conclusion: Biosurveillance using ESSENCE effectively detected and tracked changing influenza trends within the VA during the H1N1 outbreak and represents an important temporal alerting system for monitoring health events in all VA facilities.
Mark Holodniy, MD1, Cynthia Lucero, MD1, Gina Oda, MS1, Patricia Schirmer, MD1 and  P. Schirmer, None..
C. Lucero, None..
G. Oda, None..
M. Holodniy, None., (1)Department of Veterans Affairs, Palo Alto, CA