1260. Measuring risk of healthcare-associated influenza-like illness (HA-ILI) in pediatric ambulatory practices using a self-controlled case series
Session: Oral Abstract Session: Respiratory Viral Infections in Children
Saturday, October 5, 2013: 11:30 AM
Room: The Moscone Center: 200-212
Background: Despite the potential for infectious disease transmission in pediatric ambulatory settings, little is known about the epidemiology of healthcare-associated viral infection and the risk attributable to an outpatient encounter.  Our objective was to determine if prior exposure to a clinic visit in a pediatric ambulatory practice is a risk factor for influenza-like illness (ILI).  

Methods: We used electronic health record (EHR) data to enroll all children <6 years old presenting to any of 29 clinic sites within a pediatric primary care network over a respiratory viral season (9/1/12-4/30/13).  ILI cases were identified using ICD-9 codes validated for syndromic surveillance.  HA-ILI was defined as any ILI case presenting 1-8 days after a non-ILI related clinic visit based upon incubation periods of common respiratory viruses.  We constructed a self-controlled case series to allow for the implicit control of potential confounders associated with ILI risk among children.  Key parameters for this method included principal exposure (non-ILI clinic visit), risk period (1-8 days after non-ILI clinic visit) and principal event (ILI encounter). We observed all ILI cases retrospectively and prospectively to each encounter and computed the conditional likelihood of an ILI visit during a risk period using a conditional Poisson model. 

Results: Among 73,345 children <6 years old (mean age 2.2 years) with a clinic visit during the study period, there were 283,856 total and 5,666 (2.0%) ILI encounters.  Six hundred and five (10.7%) fit the case definition for HA-ILI.   Using a self-controlled case series, the incidence rate ratio (IRR) for HA-ILI was 3.56 (95% C.I. 3.23, 3.91) comparing the incidence of ILI with and without a prior clinic visit.  This estimate is sensitive to case definition, but remains significant. 

Conclusion: Preliminary results from this analytic method suggest that a pediatric clinic visit during a respiratory season is significantly associated with increased risk of developing an ILI among young children.  Ongoing work will establish the validity of an EHR-based definition of HA-ILI and identify specific factors associated with HA-ILI that can be targeted to ensure effective implementation of infection control measures in ambulatory settings.

Kristen Feemster, MD, MPH, MSHP, Pediatrics, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA; Division of Infectious Diseases, Children's Hospital of Philadelphia, Philadelphia, PA, A. Russell Localio, PhD, University of Pennsylvania School of Medicine, Philadelphia, PA; Center for Clinical Epidemiology and Biostatistics, Philadelphia, PA; The Children's Hospital of Philadelphia, Philadelphia, PA, Maria Middleton, M.P.H., Division of Infectious Diseases, The Children's Hospital of Philadelphia, Philadelphia, PA, Marianne Chilutti, M.S., Center for Biomedical Informatics, The Children's Hospital of Philadelphia, Philadelphia, PA, Joshua Metlay, MD, PhD, Center for Clinical Epidemiology and Biostatistics, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA and Susan Coffin, MD, MPH, Infectious Diseases, The Children's Hospital of Philadelphia, Philadelphia, PA

Disclosures:

K. Feemster, None

A. R. Localio, None

M. Middleton, None

M. Chilutti, None

J. Metlay, None

S. Coffin, None

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