The impact of computer-generated messages on childhood immunization coverage

INTRODUCTION: Recent evaluations of computer-generated reminder/recall messages have suggested that they are an inexpensive- labor-saving method of improving office visitation rates of childhood immunization providers. This study assesses the sustained impact of computer-generated messages on immunization coverage during the first two years of life. DESIGN: Randomized- controlled trial. SETTING: County health department in the Denver metropolitan area. STUDY PARTICIPANTS: Children (n = 1227) 60 to 90 days of age who had received the first dose of diphtheria-tetanus-pertussis (DTP) and/or poliovirus vaccines. INTERVENTION: Households of children were randomized into four groups to receive: telephone messages followed by letters (Group A)/ telephone messages alone (Group B)/ letters only (Group C)/ or no notification (Group D). Households in the intervention groups (A- B- and C) received up to five computer-generated telephone messages and/or up to four letters each time their children became due for immunization(s). MAIN OUTCOME MEASURE: Immunization series completion at 24 months of age. RESULTS: Children whose families were randomized to receive any of the interventions were 21% more likely to have completed the immunization series by 24 months of age than were children randomized into the control group (49.2% vs 40.9%/ RR rate ratio = .21/ CI confidence interval = 1.01- 1.44). While not statistically significant- children in Group A were 23% more likely to complete their immunization series by 24 months of age than those in the control group (50.2% vs 40.9%/ RR = 1.23/ CI = 1.00- 1.52). No differences were detected among the intervention groups. The costs per additional child completing the series by 24 months of age in Group A was $226 ($79 after start-up costs were discounted). CONCLUSION: Computer-generated contacts- either by phone or by mail (or both combined)- used each time vaccines become due- are efficacious in increasing immunization coverage of children under 2 years of age.