Cluster randomized trial of a toolkit and early vaccine delivery to improve childhood influenza vaccination rates in primary care

Abstract

Purpose: To increase childhood influenza vaccination rates using a toolkit and early vaccine delivery in a randomized cluster trial.

Methods: Twenty primary care practices treating children (range for n=536-8183) were randomly assigned to Intervention and Control arms to test the effectiveness of an evidence-based practice improvement toolkit (4 Pillars Toolkit) and early vaccine supplies for use among disadvantaged children on influenza vaccination rates among children 6 months-18 years. Follow-up staff meetings and surveys were used to assess use and acceptability of the intervention strategies in the Intervention arm. Rates for the 2010-2011 and 2011-2012 influenza seasons were compared. Two-level generalized linear mixed modeling was used to evaluate outcomes.

Results: Overall increases in influenza vaccination rates were significantly greater in the Intervention arm (7.9 percentage points) compared with the Control arm (4.4 percentage points; P<0.034). These rate changes represent 4522 additional doses in the Intervention arm vs. 1390 additional doses in the Control arm. This effect of the intervention was observed despite the fact that rates increased significantly in both arms - 8/10 Intervention (all P<0.001) and 7/10 Control sites (P-values=0.04 to <0.001). Rates in two Intervention sites with pre-intervention vaccination rates >58% did not significantly increase. In regression analyses, a child's likelihood of being vaccinated was significantly higher with: younger age, white race (Odds ratio [OR]=1.29; 95% confidence interval [CI]=1.23-1.34), having commercial insurance (OR=1.30; 95%CI=1.25-1.35), higher pre-intervention practice vaccination rate (OR=1.25; 95%CI=1.16-1.34), and being in the Intervention arm (OR=1.23; 95%CI=1.01-1.50). Early delivery of influenza vaccine was rated by Intervention practices as an effective strategy for raising rates.

Conclusions: Implementation of a multi-strategy toolkit and early vaccine supplies can significantly improve influenza vaccination rates among children in primary care practices but the effect may be less pronounced in practices with moderate to high existing vaccination rates. Clinical trial registry name/number: From Innovation to Solutions: Childhood Influenza/NCT01664793.

Keywords: Childhood influenza vaccination; Children; Immunization; Influenza vaccine.

Figure 1. Randomization Scheme