Evaluation of an Intervention to Improve Immunization Up-to-Date Rates Among Children Attending WIC in South Los Angeles Working together for healthy children

Contributing Authors: Presenting Author: Jennifer Chiprich, PhD Contributing Authors: Julia Heinzerling, MPH Lizz Romo, BS, RD Terry Silberman, DrPH Working together for healthy children

Background South LA Health Projects conducted IZ promotion activities at 10 South LA WIC Sites April 2006 – December 2007 AIR (assessment, information and referral) MVP (voucher incentive) Assessment, information and referral (AIR) activities include assessing children’s immunization needs, providing parents with immunization information, and referring children to their doctor to get needed immunizations (if they don’t have a medical home, we provided a referral list). MVP: Monthly Voucher Pick-up (MVP) is the strategy of issuing only 1 month of WIC vouchers, instead of the customary 2-3 months worth at a time, to participants whose children are past due for immunizations; participants return to WIC monthly until their children are current. Working together for healthy children

Background Additional intervention for parents of under-immunized children Follow-up phone calls (up to 3 attempts) Follow-up letter Tracking tool ITSLA (Immunization Tracking System Los Angeles) The intervention was done by administration staff Working together for healthy children

Study Population and Groups Children served at one of the 10 South LA WIC sites between April – December 2006 and 3 or 5 months of age and under-immunized when screened Intervention Group Children who were under-immunized and served at a WIC site on an even day of the month. (n = 600) Control group Children who were under-immunized and served at a WIC site on an odd day of the month. (n = 508) Working together for healthy children

Demographics Race/Ethnicity Intervention Control Asian 0.3 % 0.2 % African-American 15.4 7.9 Hispanic 73.9 78.6 Pacific Islander 0.3 0.2 Native American Multiracial 5.8 8.1 Refused 1.5 2.0 White 1.3 1.0 No answer 1.8 Working together for healthy children

Intervention Control group Intervention group Received MVP and AIR at WIC Intervention group Received MVP and AIR + phone call and letter Working together for healthy children

Results IZ Received Intervention Did Not Receive Intervention DTP(3) 337 (70.2%) 449 (71.7%) Polio (2) 443 (92.3%) 578 (92.3%) Hib (2) 438 (91.3%) 576 (92.0%) HepB (2) 466 (97.1%) 598 (95.5%) Up-to-Date 334 (69.6%) 447 (71.4%) There is no significant difference in proportion between the groups at 13 months. Working together for healthy children

Results Received Intervention vs. Did Not Receive 7th month IZ Chi-square P-value DTP (3) 0.2174 0.6410 Polio (2) 0.0299 0.8628 Hib (2) 0.3122 0.5763 HepB (2) 1.4330 0.2313 Up-to-date 0.2375 0.6260 13th month IZ Chi-square P-value DTP (3) 0.3040 0.5814 Polio (2) 0.0006 0.9800 Hib (2) 0.2073 0.6489 HepB (2) 1.8009 0.1796 Up-to-date 0.4348 0.5096 When examined by ‘current’ status, in an effort to decrease the attrition in the sample, the p-values remain non-significant. Current status was defined as those who had attended one of the SLAHP WIC offices in their 10-12th month and had brought their immunization cards. It was chosen to do the analysis using the receiving intervention group to show the ‘real life’ presentation of the study.

Results Change in UTD Status between 7th and 13th month Group Chi-square P-value Received vs. did not receive intervention 1.3216 0.2514 Approximately the same percentage of participants in each group changed UTD status between their 7th and 13th month: Received intervention (24.4%) Did not receive intervention (21.5%) This table shows the chi-square result comparing change in UTD status between the 7th and 13th month for the two groups. Working together for healthy children

Results Two analyses based on contact mode Receiving a letter only compared to receiving both a letter and phone contact. Receiving phone contact only compared to receiving both a letter and phone contact. There were no significant differences The significance of these results are obviously influenced by the lack of significance in the primary hypothesis. P-values for the analysis were not close to borderline significance. There were 450 in the study that received contact: 210 (46.7%) that received phone contact and 240 (53.3%) that received a letter by no phone contact. Working together for healthy children

Discussion No statistically significant difference based on chi-square analysis between the received intervention group and control group (at 13 months). Interpretation: There is no significant increase in UTD rates at the 13th month with the use of follow-up calls and letters, AIR and MVP over the UTD rates with use of AIR and MVP alone. Working together for healthy children

Discussion Bias Randomization of the subjects Blinding Other factors Media coverage of immunizations Variables not measured by the SLAHP team External validity Working together for healthy children

Comparison with the literature Similar to findings of Hoekstra et al, in Journal of Pediatrics, 1999. (1) Other findings consistent with other published work DTaP most missed vaccine by children (2) High baseline rates and effectiveness of MVP in similar populations (3) Working together for healthy children

Conclusion Based on the findings of this study, we discontinued the supplemental telephone and mail follow-up. We continue to administer AIR and MVP at all 10 SLAHP WIC sites.

Evaluation Specialist South Los Angeles Health Projects To Learn More… Jennifer Chiprich, PhD Evaluation Specialist South Los Angeles Health Projects (323) 757-7244 Ext. 287 jchiprich@slahp.org Acknowledgements Immunize LA Kids was supported by the Centers for Disease Control and Prevention (CDC) under the REACH 2010 Initiative and the California Department of Health Services Immunization Branch. Immunize LA Kids received institutional support from the Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center. Working together for healthy children

References 1. Hoekstra EJ, LeBaron CW, Johnson-Partlow T, Does reminder-recall augment the impact of voucher incentives on immunization rates among inner-city infants enrolled in WIC?, J Pediatr. 1999 Aug; 135(2 Pt 1): 261-3. 2. Ghosh TS, Patnaik JL, Bennet A, Trefren L, Vogt RL; Assessment of missing immunizations and immunization-related barriers among WIC populations at the local level. Public Health Rep. 2007 Sep-Oct; 122(5):602-6. 3. Ashkar SH, Dales LG, Averhoff, F, Shefer A, Higa J, et al. The effectiveness of assessment and referral on immunization coverage in the special supplmenetal nutrition program for women, infants and children. Arch Pediatr Adolesc. Med. 2003 May; 157(5): 456-62. Working together for healthy children