Abstract
Objective.
Weight assessment is a critical aid in patient care. It is particularly important in monitoring progression of pregnancies, heart failure status, and when adjusting medications. Although weight is generally determined using a scale, few studies have evaluated the precision of non-household scales. The objective of this study was to assess scale precision across a variety of settings.
Methods.
An evaluation of scales from randomly selected primary care clinics (n=30), diabetology/endocrinology clinics (n=7), weight loss facilities (n=25), and fitness centers (n=30) was performed. Assessments were completed on a total of 223 scales: 94 from primary care clinics, 32 from diabetology/endocrinology clinics, 39 from weight loss centers, and 58 from fitness centers. Scales were assessed for condition, location in facility, resting surface, commercial designation, and calibration history. Scale precision was validated using 100 lb. (45.5 kg), 150 lb. (68.3 kg), 200 lb. (90.9 kg), and 250 lb. (113.6 kg) certified weights.
Results.
Overall, scales demonstrated decreased precision with increased weight. At higher weights, more than 15% of scales were off by more than 6 lbs. (2.3 kg), approximately 1 Body Mass Index (BMI) unit. While facility type was not significant, condition, location in facility, resting surface, commercial designation, and calibration history were significant.
Conclusions.
This study demonstrates that many scales used to measure body weight are imprecise and that scales in health care settings are no more precise than those in other facilities. Clinical decisions based on scales that are imprecise have the potential to cause iatrogenic complications in patient care.