The Effect Of Hand Cleanliness On Bioelectrical Impedance Analysis Measurements Compared To Air Displacement Plethysmography

BACKGROUND: CDC recommendations for handwashing continue to be advocated, however it is unclear how these recommendations affect BIA accuracy. PURPOSE: The purpose of this study was to determine the effect of “unclean” hands, hands washed with soap and water, and hand sanitizer on the accuracy of body composition assessed by a hand-held bioelectrical impedance analyzer as compared to air displacement plethysmography. METHODS: Air displacement plethysmography (BP) was performed on 78 participants (23.1±5.8 years, 68.1±4.3 in, 174.0±37.1 lbs, 40 women). Participants underwent BIA assessments with hands that were unwashed for at least two hours prior to reporting to the lab (B1), again after following CDC recommendations for soap and water washing (B2), and for a third time following CDC recommendations for hand sanitizer usage (B3). RESULTS: A repeated measures ANOVA, with a Greenhouse-Geisser correction, determined that mean scores for percent body fatness differed significantly between assessment types (F(1.033, 79.51) = 29.18, p < 0.001). Post hoc testing using the Bonferroni correction revealed no difference in BIA conditions (B1-19.5±6.9%, B2-19.6±6.9%, B3-19.6±6.9%), yet all were significantly lower than BP (BP-22.2±8.9%). There were statistically significant correlations between BP and all BIA conditions (r = 0.88, p<0.05). Using a Bland-Altman analysis, there were statistically significant positive correlations between BP and all BIA conditions (r = 0.49, p<0.05). Interestingly, the standard error of the estimate was lowest for soap and water washing (B1 - 3.26, B2 - 3.20, B3 - 3.22), albeit modest differences between conditions. CONCLUSION: There was a difference between percent fat values from BP and BIA conditions (B1, B2, and B3) following a means comparison analysis. Additionally, correlations yielded strong statistical similarities between BP and BIA. While no hand conditions differed from each other, the predictability of the BIA lessened as the percent values increased. Furthermore, the standard error of the estimate revealed that percent fat estimations were lowest following washing hands with soap and water. Cleanliness of hands does not appear to affect BIAs ability to estimate body composition. Although, BIAs ability to estimate does weaken as percent fat values increase.