Age-appropriate compliance and completion of up to five doses of pertussis vaccine in US children

Background: In the United States (US), diphtheria, tetanus, and acellular pertussis (DTaP) vaccination is recommended at 2, 4, and 6 months (doses 1–3), 15–18 months (dose 4), and 4–6 years (dose 5). The objective of this study (GSK study identifier: HO-14–14383) was to examine DTaP completion and compliance rates among commercially insured and Medicaid-enrolled children. Secondarily, the study aimed at identifying predictors of compliance/completion. Methods: Truven Health MarketScan Commercial and Multi-State Medicaid databases (2005–2013) were analyzed separately. Children born during 2005–2011 with ≥ 2 years continuous enrollment from birth provided data for doses 1–4; those with continuous enrollment from birth to their seventh birthday provided dose 5 data. Series compliance (each recommended dose by 3, 5, and 7 months; 19 months; seventh birthday) and completion (3 doses by 8 months; 4 by 24 months; 5 by seventh birthday) were calculated. Predictors of compliance/completion were identified using multivariable logistic regression. Results: A total of 367,493 commercially insured and 766,153 Medicaid-enrolled children were followed for ≥ 2 years; and 23,574 and 41,284, respectively, for ≥ 7 years. Series compliance to doses 1–3, 1–4, and 1–5 were 67.2%, 55.3%, 47.5% (commercial) and 37.4%, 27.3%, 14.4% (Medicaid), respectively. Predictors of better compliance/completion included: later birth year (commercial/Medicaid) and higher household income (commercial); predictors of worse compliance/completion included: Northeast residence (commercial), birth hospitalization ≥ 14 days (commercial/Medicaid), and Black race/ethnicity (Medicaid). Conclusions: DTaP series compliance/completion improved over time, but appear to be suboptimal. As this could increase pertussis risk, greater awareness of the importance of timely vaccination completion is needed. GSK study identifier: HO-14–14383