Pediatric Academic Societies Abstracts for 2001

MEASURING IMMUNIZATION RATES IN OFFICE PRACTICE: A STUDY FROM PROS AND THE NMA PM Darden, JA Taylor, DA Brooks, AB Bocian, JW Hendricks, JM Stevenson and M Massoudi. Pediatrics, MUSC, Charleston, SC; University of Washington, Seattle, WA; Johns Hopkins University, Baltimore, MD; PROS, Center for Child Health Research, American Academy of Pediatrics, Elk Grove Village, IL; Pediatric & Adolescent Care, Tulsa, OK; and NIP, CDC, Atlanta, GA. Accepted for a poster symposium presentation at the 2001 Pediatric Academic Societies? Annual Meeting.

BACKGROUND: Measuring practice immunization rates is indispensable to improving these rates. Our previous study suggested that review of consecutive patient records yielded a simple and valid measure of practice immunization rates.

OBJECTIVE: To compare three methods for measuring immunization rates in pediatric office practice in a national sample of practices.

DESIGN/METHODS: Immunization rates were determined for each practice using three methods. The Consecutive Method - data from the practice medical record of patients aged 8-19 months seen consecutively in the office. The CASA Method, data was collected in a standard manner by local health departments using a CDC software program, CASA. CASA data were randomly selected medical records of patients aged 19-35 months. The Active Method (reference standard) combined CASA data with a telephone interview of parents to collect current patient status and parent-held immunization data (only data on current patients was used). Complete data were received from 33 practices in 22 states. Analyses were based on patients in each practice at 19 months of age. There were a mean of 38/156/40 (Consecutive/CASA/Active Method) evaluable patients per practice. Patients were fully immunized if they had received 4 DTP/DTaP/DT, 3 Polio, 3 Hib, 1 MMR and 3 Hep B by 19 months of age. Comparisons between the CASA and consecutive methods and the reference standard were made with paired t-tests.

RESULTS: The mean immunization rates at 19 months were: Consecutive 69.5% (range 32-90), CASA 61.3% (22-88), Active (reference standard) 68.6% (44-88). Within a given practice, the differences between methods were considerable. The Consecutive minus Active difference in each practice varied from -28 to 30 percentage points (PP). The CASA minus Active difference was -23 to 10 PP. The mean difference from the Active Method was -7.3 PP (P<.001) when compared with the CASA Method and 0.9 percentage points (P=.65) for the Consecutive Method.

CONCLUSIONS: Different methods of measuring immunization rates will give different results. Pediatric practices monitoring their immunization rates should consider using the Consecutive Method, it is a simple, acceptable and valid measure of practice immunization rate.

DISCLOSURE: Funding from CDC, National Immunization Program, and HRSA, Maternal and Child Health Bureau.