Bestämning av kroppssammansättning hos överviktiga och obesa ammande kvinnor. Validering av bioelektrisk impedans mot röntgenabsorption.
Bioelektrisk impedansspektroskopi (BIS)KroppssammansättningPostpartumRöntgenabsorption (DXA)ValideringBioelectrical impedance spectroscopy (BIS)Body compositionDual energy xray absorptiometry (DXA)PostpartumValidation
Introduction: Pregnancy, obesity, aging and certain diseases are examples of conditions thataffect the body, its constitution and composition. Simpler methods to estimate bodycomposition are needed to complement more advanced traditional methods to better identifythe health status without sacrificing accuracy and precision.Objective: To validate the results of body composition from bioelectrical impedancespectroscopy (BIS) against results from the study reference method, dual energy X-rayabsorption (DXA), in overweight and obese lactating women after childbirth.Method: The design of the LEVA-study (Lifestyle for Effective Weight loss during lactation)consisted both intervention and longitudinal follow-up, which gave the opportunity tovalidate the absolute values (accuracy) and the ability to detect changes (precision). Themean difference between methods was tested statistically by paired t-test. Bland-Altman plotsused to examine the degree of agreement between BIS and DXA, but also distribution andany systematic differences. Association between methods was measured by using Pearson´scorrelation coefficient.Results: Between BIS and DXA, absolute measurements of the variables fat-free mass (FFM)and fat mass (FM) showed a statistically significant difference (p < 0.001). Analysis ofchanges over time showed no significant difference between BIS and DXA in the samevariables (p > 0.05). Analysis of total muscle mass gave no significant difference betweenBIS and DXA, either in absolute values or in change (p > 0.05).Conclusion: At group level, BIS may not be completely accurate to estimate bodycomposition in women (BMI 25-35) postpartum at absolute measurements if compared withresults from DXA. However, BIS demonstrated changes equivalent to DXA when measuringthe same variables over time. On group level, total body skeletal muscle mass (TBSMM)calculated from BIS did not statistically differed from DXA, either absolute values or change.