Randomized controlled trial of an immunization recall intervention for adolescents.

Objective: Determine if adolescent immunization rates can be improved by contacting the parents or by contacting both the parents and adolescents.

Methods: Thirteen- to 17-year-olds overdue for at least 1 of 3 immunizations were randomized to (1) a control arm (Control), (2) telephone calls to the parent/guardian (Parent Only), or (3) telephone calls to the parent/guardian and the adolescent (Parent/Adol). Immunization records were assessed 4 weeks and 1 year after the intervention. Two-sided χ(2) tests and logistic regression models were used to compare receipt of immunizations by study arm.

Results: The intention-to-treat analysis showed improved immunization rates at 4 weeks (adjusted odds ratio 2.27, 95% confidence interval 1.00-5.18), but not at 1 year, in the Parent/Adol group compared with controls. There was a trend toward increased immunization in the Parent Only group (odds ratio 2.02, 95% confidence interval 0.89-4.56). However, phone contact was not achieved for many parents and adolescents in the intervention groups. A post hoc analysis of the impact of actual phone contact showed significant improvement in immunization rates both 4 weeks and 1 year after the intervention among those who were reached successfully.

Conclusions: Improvement in immunization rates was seen in the short term but not the long term after contacting both the parent and adolescent. Although telephone interventions may be effective when rapid immunization is necessary, the difficulty in reaching parents and adolescents by phone highlights the importance of up-to-date contact information and a need to assess the effectiveness of alternative means of communication.