Measuring body mass index according to protocol: how are height and weight obtained?

Previous investigation at our resident-teaching, family medicine clinics determined that >80% of adult patients have body mass index (BMI) recorded in the electronic medical record. The quality of this measure, however, is not known. The objective of this study was to determine the accuracy of documented BMI. We used an observational study design to determine the means by which clinic staff obtain height and weight values from patients. We found that staff only obtained 35.4% of these measurements according to protocol. The major reason for noncompliance with protocol was that shoes were not removed for the measurements. Our investigation indicated that providers, quality improvement teams, and researchers should not assume the accuracy of the recorded BMI. Future investigation is warranted to improve the quality of these measurements in the outpatient setting.