Immunization performance measurement in a changing immunization environment

The measurement of performance in the delivery of recommended vaccinations for children is used frequently as a marker for quality of care and as an outcome for studies of interventions to improve immunization coverage levels. The critical element of immunization performance measurement is the determination of immunization status. This methodologic review 1) discusses immunization status as a measure of quality of primary care for children, 2) describes immunization status measures used in immunization intervention studies, and 3) examines selected technical issues of immunization status measurement. 1) Description of the characteristics of immunization status measurements obtained by a systematic review of studies published between 1980 and 1997 on interventions to raise immunization coverage, and 2) illustration of technical considerations for immunization status measurement using one local database and one national database of immunization histories. Technical issues for immunization status measurement include 1) the need to use documented immunization histories rather than parental recall to determine immunization status, 2) the need to link records across providers to obtain complete records, 3) the sensitivity of immunization status to missing immunization data, and 4) the potential of measures incorporating combinations of immunizations to underestimate the degree of vaccination in a population. Immunization performance measurement has many characteristics of a robust quality of care measure, including high acceptance by primary care providers of routine vaccination, association of immunization status with the conduct of other clinical preventive services, agreed-on technical and programmatic standards of care, and legislative requirements for medical record documentation. However, it is not without challenges. Careful attention to technical issues has potential to improve immunization delivery health services research.