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

Abstract 

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.

Keywords: Diagnosis code, Urticaria, Vaccine safety surveillance, Influenza vaccine, Predictive value, Claims databases