Does a pay-for-performance program for primary care physicians alleviate health inequity in childhood vaccination rates?

INTRODUCTION: Childhood vaccination rates in Manitoba populations with low socioeconomic status (SES) fall significantly below the provincial average. This study examined the impact of a pay-for-performance (P4P) program called the Physician Integrated Network (PIN) on health inequity in childhood vaccination rates. METHODS: The study used administrative data housed at the Manitoba Centre for Health Policy. We included all children born in Manitoba between 2003 and 2010 who were patients at PIN clinics receiving P4P funding matched with controls at non-participating clinics. We examined the rate of completion of the childhood primary vaccination series by age 2 across income quintiles (Q1–Q5). We estimated the distribution of income using the Gini coefficient, and calculated concentration indices for vaccination to determine whether the P4P program altered SES-related differences in vaccination completion. We compared these measures between study cohorts before and after implementation of the P4P program, and over the course of the P4P program in each cohort. RESULTS: The PIN cohort included 6,185 children. Rates of vaccination completion at baseline were between 0.53 (Q1) and 0.69 (Q5). Inequality in income distribution was present at baseline and at study end in PIN and control cohorts. SES-related inequity in vaccination completion worsened in non-PIN clinics (difference in concentration index 0.037; 95 % CI 0.013, 0.060), but remained constant in P4P-funded clinics (difference in concentration index 0.006; 95 % CI 0.008, 0.021). CONCLUSIONS: The P4P program had a limited impact on vaccination rates and did not address health inequity.