METHODOLOGICAL ISSUES IN DETERMINING RATES OF CHILDHOOD IMMUNIZATION IN OFFICE PRACTICE - A STUDY FROM PEDIATRIC RESEARCH IN OFFICE SETTINGS (PROS)

Objective: To compare 3 methods for measuring pediatric office immuniz ation rates. Design: Retrospective and prospective cross-sectional sur veys. Patients: Children 2 and 3 years old from 15 pediatric practices in 11 states.Methods: Immunization rates were determined for each pra ctice using 3 methods. The Consecutive method used data from the pract ice's medical records of patients seen consecutively in the office; th e Chart method used data from randomly selected practice medical recor ds; and the Active method (reference standard) used a combination of m edical record data with a telephone interview to collect additional im munization data and current patient status, using data only on current patients. Analyses were based on a mean of 57, 62, and 51 (Consecutiv e, Chart, and Active method, respectively) patients per practice. Pati ents were considered fully immunized if they had received 4 doses of D TP/DT vaccine, 3 doses of OPV/IPV, and 1 dose of MMR vaccine by their second birthday. Comparisons were made using the paired t test. Result s: The mean immunization rate by method was Consecutive, 81.5% (range, 51%-97%); Chart, 71.6% (range, 42%-94%); and Active, 79.6% (range, 53 %-96%). Within a given practice, the differences between methods varie d considerably (0 to 28 percentage points). The mean difference from t he reference standard Active method was 8 percentage points (P<.001) f or the Chart method and -1.9 percentage points (P=.36) for the Consecu tive method. The largest difference was between the Consecutive and Ch art methods (mean difference, 9.9 percentage points; P=.003). Practiti oners uniformly found the Consecutive method easiest to implement. Con clusions: Practice-specific immunization rates are one of the few obje ctive measures of the quality of preventive pediatric care. Pediatric practices monitoring their immunization rates should consider using th e Consecutive method, a simple, acceptable, and valid measure of pract ice immunization rate.