Outpatient urticaria diagnosis codes have limited predictive value for same-day influenza vaccine adverse event detection.

OBJECTIVES: To assess the predictive value of claims-based outpatient urticaria diagnosis codes to identify potential vaccine-related adverse events (AEs) when recorded on the same day as influenza vaccination. STUDY DESIGN AND
SETTING: Health plan members with outpatient claims for influenza vaccination and urticaria on the same day between October 1, 2002, and December 31, 2007, were eligible for inclusion. Electronic medical records (EMRs) for 50 eligible patients with the most recent visits of interest occurring at a large group practice were sampled for review.
RESULTS: EMRs were available and reviewed for 42 of 50 patients. An influenza vaccination was confirmed in all reviewed medical charts. Urticaria occurring on the day of influenza vaccination was confirmed for 40% of participants (17/42); 3 confirmed urticaria diagnoses were potential AEs and 14 urticaria events occurred before vaccination. Among those with unconfirmed diagnoses, 17 had no evidence of urticaria on physical examination on the day of interest (4 had evidence of a nonurticarial rash and 13 had no evidence of rash on examination) and 8 had insufficient information to make a clinical determination.
CONCLUSION: Outpatient diagnosis codes for urticaria found in health insurance claims data are limited in their predictive value to identify same-day vaccine AEs. Copyright 2010 Elsevier Inc. All rights reserved.