The impact of record scattering on the measurement of immunization coverage

Background. Lack of a consolidated immunization record may lead to problems with determining individual immunization needs at office visits as well as measuring vaccination coverage levels of a clinician's practice or a commu nity's population. Objectives. For children with multiple immunization providers, evaluate the difference in coverage levels using data from all responding immunization providers compared with: 1) the most recent immunization provider's records , 2) the first immunization provider's records, and 3) a randomly selected immunization provider's records. Identify characteristics of the most recen t provider that may be associated with reporting incomplete immunization hi stories. Methods. Data from the 1995 National Immunization Provider Record Check Stu dy (NIPRCS) were used for analysis. The NIPRCS is a provider validation stu dy of the household reported immunization histories of all children 19 to 3 5 months of age included in the National Health Interview Survey (NHIS). Pr oviders identified by the child's parent during the NHIS interview are mail ed a 2-page survey to report all immunizations (type and date) the child re ceived, regardless of the provider who administered the shots, and child's first and most recent visit dates to the practice. Results. Of the 1352 children with provider data, 304 (22%) had received im munizations from more than one provider. Compared with information from all providers and depending on the vaccine, the most recent provider records u nderestimated coverage by 9.6 to 13.4 percentage points; the initial provid er records underestimated coverage by 15.6 to 34.6 percentage points; and t he randomly selected provider records underestimated coverage by 10.0 to 20 .7 percentage points. Public facilities and having an immunization summary sheet in the patient's chart were associated with having complete records. Conclusion. Scattered immunization records significantly compromise the abi lity of clinicians to determine the immunization status of their patients w ho received immunizations at other sites of health care. Routinely assessin g immunization coverage levels at the practice level, implementing a recall system, and developing community-wide immunization registries are some str ategies to reduce the problem of scattered immunization records.