Validity of bioimpedance for assessment of fat-free mass in women with Rheumatoid Arthritis compared to non-rheumatic controls

The applicability of a commercial 3DO body scanner in measuring body composition in Chinese adults with overweight and obesity: a secondary analysis based on a weight-loss clinical trial

BACKGROUND

A commercial three-dimensional optical (3DO) scanning system was reported to be used in body composition assessment. However, the applicability in Chinese adults has yet to be well-studied.

METHODS

This secondary analysis was based on a 16-week weight-loss clinical trial with an optional extension to 24 weeks. Waist and hip circumference and body composition were measured by 3DO scanning at each follow-up visit during the study. Bioelectrical impedance analysis (BIA) was also performed to confirm the reliability of 3DO scanning at each visit. We used Lin's concordance correlation coefficients (CCC) to evaluate the correlation between the two methods above-mentioned. Bland-Altman analysis was also performed to evaluate the agreement and potential bias between different methods.

RESULTS

A total number of 70 Chinese adults overweight and obese (23 men and 47 women, aged 31.8 ± 5.8 years) were included in the analysis, which resulted in 350 3DO scans and corresponding 350 BIA measurements. The percent body fat, fat mass, and fat-free mass were 33.9 ± 5.4%, 26.7 ± 4.6 kg, and 50.3 ± 8.7 kg before the trial by 3DO scanning. And they were 30.5 ± 5.8%, 22.5 ± 4.7 kg, and 49.4 ± 8.3 kg after 16 weeks of the trial. Compared with BIA, 3DO scanning performed best in the assessment of fat-free mass (CCC = 0.89, 95%CI: 0.86, 0.90), then followed by fat mass (CCC = 0.76, 95%CI: 0.71, 0.80) and percent body fat (CCC = 0.70, 95%CI: 0.64, 0.75). Subgroup analysis showed that 3DO scanning and BIA correlated better in women than that in men, and correlated better in measuring fat-free mass in participants with larger body weight (BMI ≥28.0 kg/m2) than those with smaller body weight (<28.0 kg/m2).

CONCLUSIONS

3DO scanning is an effective technology to monitor changes in body composition in Chinese adults overweight and obese. However its accuracy and reliability in different ethnicities needs further exploration.

The Bioimpedance Phase Angle may be Associated With Frailty in Rheumatoid Arthritis Patients: Results From a Prospective, Cohort Study

OBJECTIVES

This study investigated whether the phase angle (PhA) on bioelectrical impedance analysis (BIA) is related to frailty in rheumatoid arthritis (RA) patients.

METHODS

Data from a prospective cohort study of RA patients were analyzed. The PhA was assessed by the BIA method, and frailty was assessed by the Kihon Check List (KCL) annually. The cutoff value of the PhA for frailty was calculated by receiver-operating characteristic analysis. The relationships between the PhA and frailty were evaluated by logistic regression analysis. The relationships between the change in PhA and frailty status and the KCL score were evaluated by analysis of covariance and multiple regression analysis.

RESULTS

A total of 170 patients (81.2% female, 66.2±13.1 years) were included in the analysis. A PhA of less than the cutoff for frailty was significantly associated with frailty (odds ratio: 4.75, 95% confidence interval: 1.86-12.17). Change in the PhA was significantly associated with change in the KCL score (β = -0.15). In robust patients, there was a significant difference in the rate of change of the PhA between the group that became pre-frail in the next year and the group that remained robust.

CONCLUSIONS

The PhA may be associated with frailty in RA patients.