Health System-Based HPV Vaccine Reminders: Randomized Trial Results

Abstract

Abstract Purpose: Evaluate the impact of health system-based outreach and reminders on human papillomavirus (HPV) vaccine series initiation and completion. Methods: We conducted a 12-month randomized trial at an integrated care system in the Pacific Northwest in 2015–2016. Parents of 10–12 year olds who had not received any doses of HPV vaccine were randomized to an intervention group (mailed letter and brochure followed by an interactive voice recognition (IVR) reminder call encouraging HPV vaccine initiation) or usual care control group. Parents could opt in to receive future messages via SMS text message on all calls. Parents of intervention group children who initiated vaccination were re-randomized to receive either no further reminders or reminders for doses 2/3. We interviewed a subset of 50 parents to assess acceptability of the program. Outcomes were HPV vaccine initiation (within 12 months or 120 days of the initial letter), on-time series completion (within 210 days of initiation), and time to vaccination, assessed with Kaplan-Meier survival analyses. Results: 1624 children were eligible for randomization (46% age 10, 32.9% age 11, 20.4% age 12). The sample was 48.3% female and 64.6% white. Rates of overall HPV vaccine initiation were similar between the intervention and control groups (49.0% and 45.8%, P = 0.26), but initiation within 120 days of outreach was higher in the intervention group (23.6% and 18.8%, P = 0.04). This effect continued through to completion within 12 months (10.3% vs. 6.8%, P = 0.04). Opt-in rates to SMS were low: 24 people completed the opt-in process. Rates of on-time series completion were similar in those who received dose 1 reminders only compared to those who received reminders for all vaccine doses (12.1% and 19.7%, P = 0.10); time-to-completion results were similar. Parent interviews suggested reminders were acceptable and useful. Conclusion: Reminder calls after an outreach letter led to more timely vaccine initiation and overall completion. Reminders beyond the initial letter and reminder call did not appear to impact vaccine series completion. The program was acceptable to parents, though there was low uptake of SMS reminders.