BACKGROUND:
In 1999, the National Vaccine Advisory Committee recommended that the Centers for Disease Control and Prevention (CDC) characterize the costs of immunization registries.

OBJECTIVE:
This paper describes the average costs of developing and maintaining a state- or city-level immunization registry and examines factors influencing costs per patient record and efficiency.

METHOD:
Data were obtained from a survey of a randomized stratified sample of registries. The final sample included 24 of the 56 registries receiving federal immunization grants for the five year period between 1998 and 2002. The annual cost to the grantee registry per patient record was calculated. A transcendental logarithmic average cost function was then estimated using a random effects weighted least squares model. Explanatory variables included: wages of operations and development staff; spending on capital equipment; proportion of physicians participating in the registry; achievement of immunization registry minimum functional standards; and number of patient records.

RESULT:
For the full sample, the median annual cost per record was $1.70. Sixteen (13.3%) of 120 registry site-years reported zero patients recorded for the entire year. This highly skewed distribution was largely attributable to development costs, accounting for an average 36% of total costs per site.
Results from the translog cost model indicated that average total costs per record were significantly influenced by the degree of registry functionality and level of participation by children and providers. Most importantly, results indicated the availability of substantial economies, with efficient size occurring between 2.15 million and 2.35 million records. Six (25%) of 24 registry sites met or exceeded efficient size during the study period.

CONCLUSION:
Most immunization registries are still developing in terms of functionality and provider and child participation, therefore average costs remain high. As registries become more fully functional and participation increases, average costs will decline. Achievement of efficient size is a realistic objective.

LEARNING OBJECTIVES:
Characterize economies available to immunization registries and factors influencing costs.