Objectives: Despite long-standing recommendations to provide annual influenza vaccination to children with chronic medical conditions, immunization rates are <10% in most primary care settings. Many obstacles impede implementation of these recommendations, including the challenge of identifying targeted children and the need to immunize yearly in a short time interval. The objective of this study was to assess the accuracy of billing data for identifying children who have high-risk conditions (HRCs) and need influenza vaccination and 2) to evaluate the efficacy of reminder/recall for children with HRCs.
Methods: The study was conducted in 4 private pediatric practices in metropolitan Denver, Colorado, that share a computerized billing system and also participate in an immunization registry. For all children aged 6 to 72 months, registry records were linked with the billing database. Patients with >or=1 encounters for an HRC in the previous 24 months were selected, with HRCs identified from International Classification of Diseases, Ninth Revision, Clinical Modification diagnostic codes. Using medical records as the "gold standard," we reviewed 327 randomly selected records to determine the sensitivity, specificity, and accuracy of billing data for identifying HRCs. For children with an HRC, we then conducted a randomized, controlled trial of reminder/recall for influenza vaccination. The primary outcome of the recall trial was receipt of influenza vaccine.
Results: Billing data had a sensitivity of 72% (95% confidence interval [CI]: 48%-95%), specificity of 95% (95% CI: 90%-100%), and overall accuracy of 90% (95% CI: 84%-96%) in determining which children had an HRC. Of the 17,273 patients aged 6 to 72 months, 2007 had >or=1 HRCs (12% overall; range: 9%-14% per practice). Asthma/reactive airways disease accounted for 87% of all HRCs. Reminder/recall significantly increased influenza immunization in children with HRCs, with a vaccination rate of 42% in those recalled, compared with 25% in control subjects. Recalled subjects were more likely to have an office visit (68% vs 60%) and less likely to have a missed opportunity to immunize (28% vs 37%) compared with control subjects.
Conclusions: Diagnosis-based billing data accurately identified children who had HRCs and needed annual influenza vaccination, and registry-driven reminder/recall significantly increased influenza immunization in targeted children.