Medicaid reimbursement affects influenza vaccination

**Yoo BK. Pediatrics. 2010;126:e998-e1010.**

Medicaid use was associated with higher influenza vaccination rates, especially among poor children, according to published study results.

Researchers from the University of Rochester School of Medicine and Dentistry in New York collected National Immunization Survey data from 2005-2006, 2006-2007 and 2007-2008 influenza seasons for children aged 6 to 23 months. They then divided the children into three economic tiers — poor, near-poor and nonpoor — and compared the information with varying levels of statewide Medicaid reimbursement.

“Although other studies noted variations in influenza vaccination rates according to insurance type, this is the first study, to our knowledge, that estimated the association between Medicaid provider reimbursement rates and childhood influenza vaccination rates,” the researchers wrote.

Results revealed that 21% of children were fully vaccinated in 2005-2006, 21.3% in 2006-2007 and 28.9% in 2007-2008. Vaccination rates differed by approximately 10 percentage points between poor and near-poor and near-poor and nonpoor children during all three seasons.

Data also demonstrated that poor children were 40% as likely to be vaccinated compared with nonpoor children during 2005-2006. Medicaid reimbursement rates were not associated with coverage levels for all children, although a significant positive relationship appeared among poor children.

The researchers found a similar association during the 2006-2007 season, with poor children appearing 35% as likely to be fully vaccinated compared with nonpoor children (OR=0.35; 95% CI, 0.21-0.68). State Medicaid reimbursement rates were again significantly linked to vaccination among poor children (OR=1.07; 95% CI, 1.01-1.13).

During 2007-2008, however, a positive relationship with the Medicaid reimbursement rate only existed for poor children in 24 states with lower capitated-payment penetration (OR=1.05; 95% CI, 1.01-1.09) compared with poor children in other states (OR=0.99; 95% CI, 0.94-1.04).

“This result supported our additional hypothesis that providers who were reimbursed mainly through capitated payments would be less sensitive to fee-for-service-based Medicaid reimbursement rates,” the researchers wrote.

A $10 increase in Medicaid reimbursement rates from the US average of $8 to $18, the highest among all states, was linked to a six percentage-point increase in the state mean of full vaccination rates during 2005-2006. The researchers also found a 9.2 percentage-point increase for the 2006-2007 season and a 6.4 percentage-point increase for the 2007-2008 season.

“Because [our study provides implicit evidence at the national level], our results could be used for a cost-effectiveness or cost/benefit simulation analysis of a future state/federal policy to increase reimbursement rates and also for justification of a future randomized controlled study to examine how an increase in Medicaid reimbursement rates for administration of vaccines may affect provider vaccination behavior,” the researchers wrote.

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