KEYWORD1:
Vaccination coverage; immunization registry; assessment method

BACKGROUND:
Chart audits using CASA are the gold standard for practice coverage assessments, but they are time and labor intensive. Immunization registries offer the potential for reliable and timely assessments using the same methodology.

OBJECTIVE:
To simulate chart audits using CASA methodology with an immunization registry

METHOD:
Using CASA standard methodology, in October 2001 and April 2002 we conducted registry-based immunization coverage assessments at a practice network serving a low-income, minority community in New York City. Eligible children were 6 to 35 months old who had made at least one visit to the practice. Following CASA procedures, we randomly sampled 3,438 children. We compared this to a 100% sample assessment, which included all eligible children in the registry (n = 16,073). Outcome measures were age-appropriate immunization rates for DTaP, Polio, MMR, Hib, and HepB (4:3:1:3:3).

RESULT:
The CASA sample and 100% record methodologies yielded comparable coverage rates. The difference between the two assessments ranged from 0.6% to 2.7% for Oct 2001 and from 1.4% to 2.9% for Apr 2002. The difference in coverage rate was smallest for children 6-11 months of age.

CONCLUSION:
When using immunization registries for practice coverage assessments, random sampling using CASA methodology yields comparable results to universal evaluation. This is a cost-effective alternative for practices with a very large patient population and limited computer time.
LEARNINGOBJECTIVES:
Sample methodology for registry-based assessments