The Impact of a Group Health Cooperative HPV Vaccination Promotion Program on Initiation of the HPV Vaccine

Thesis (Master's)--University of Washington, 2016-06

Purpose: The purpose of this study is to examine the impact of a Group Health Cooperative outreach and reminder program on initiation of the HPV vaccine among 10-12 year olds receiving care at seven Group Health clinics in Western Washington. Study Design: The outreach and reminder initiative was a randomized control trial. Eligible children were randomized to receive an outreach letter and reminder calls about the HPV vaccine (intervention) or usual care (control). Randomization was at the child-level and stratified by clinic and gender, but outreach and reminder efforts were addressed and targeted to parents. Methods: This study conducted a preliminary analysis of the impact of the outreach and reminder program on initiation of the HPV vaccine for the overall study population and stratified by age. Chi-square tests were used to assess associations between group assignment (intervention or control) and receipt of HPV dose 1. Kaplan-Meier survival curves with log-rank tests were used to compare HPV vaccine initiation over time between the intervention and control groups. Results: A total of 1,805 children were included in the study; 1,354 were randomized to the intervention and 451 to control. Our analysis included 1,770 children after excluding 35 children who disenrolled after randomization, but before the intervention began. Overall, the intervention was not significantly associated with initiation of the HPV vaccine; 398 (30.1%) intervention children received HPV dose 1 compared to 121 (27.1%) control children (Chi-square test, p=0.23). There was also no association between the intervention and initiation of the HPV vaccine when the children were stratified by age (Chi-square test, 10 yrs, p=0.78; 11 yrs, p=0.31; 12 yrs, p=0.38). The Kaplan-Meier analyses showed that the difference in the vaccine initiation rates between the groups was not significant, overall (Log-rank test, p=0.08), nor when the children were stratified by age (Log-rank test, 10 yrs, p=0.71; 11 yrs, p=0.10; 12 yrs, p=0.31). Yet, a secondary analysis looking at vaccine initiation from the start of the reminder calls to the end of the analysis period showed a 6.2% difference in vaccine initiation rates between the intervention and control groups for 11 year olds (Chi-square test, p=0.07, Log-rank test, p=0.06). Conclusions: Group Health’s outreach and reminder program was not significantly associated with an increase in initiation of the HPV vaccine. However, while not significant, our data suggests that reminder calls may increase the initiation of the HPV vaccine among 11 year old children eligible for the vaccine in an insured population.