Accepted for/Published in: JMIR mHealth and uHealth
Date Submitted: Jul 13, 2020
Date Accepted: Dec 12, 2020
Accuracy of three smart scales for weight and body composition in adults
ABSTRACT
Background:
Smart scales are increasingly used at home by patients to monitor their body weight and body composition, but their accuracy has not often been documented.
Objective:
To determine the accuracy of three commercially available smart scales for weight and body composition, compared to DEXA as gold standard.
Methods:
We designed a cross-sectional study in patients addressed for DEXA in a physiology unit in a tertiary hospital in France. We consecutively included adult patients addressed for DEXA. There were no exclusion criteria except patient declining to participate. Patients were weighed with one smart scale immediately after DEXA. Three different scales were compared (Téfal Body Partner, Teraillon dietpack, Nokia Withings Body Cardio). We determined absolute error between gold-standard values obtained from DEXA and from smart scales for body mass, fat mass and lean mass.
Results:
The sample for analysis included 53, 52 and 48 patients for each of the three tested smart scales respectively. The median absolute error for body weight was 0.3kg (IQR -0.1;0.7), 0.0kg (IQR -0.4;0.3) and 0.25 kg (IQR -0.10; 0.52) respectively. For fat mass, absolute errors were -2.2kg (IQR -5.8;1.3), -4.4kg (IQR -6.6;0.0) and -3.7kg (IQR -8.0;0.28) respectively. For muscular mass, absolute errors were -2.2kg (IQR -5.8;1.3), -4.4kg (IQR -6.6; 0.0) and -3.65kg (IQR -8.03;0.28) respectively. Factors associated with fat mass measurement error were weight for scales 1 and 2 (P=0.03 and P<.001 respectively), BMI for scales 1 and 2 (P=0.034 and P<.001), body fat for scale 1 (P<.001) and muscular and bone mass for scale 2 (P<.001 for both). Factors associated with muscular mass error were weight and BMI for scale 1 (P<.001 and P=.004), body fat for scales 1 and 2 (P<.001 for both) and muscular and bone mass for scale 2 (P<.001 and P=.002 respectively).
Conclusions:
Smart scale are not accurate for body composition and should not replace DEXA in patient care. Clinical Trial: National Clinical Trials 03803098
Citation
Per the author's request the PDF is not available.
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