| dc.description.abstract | Background: Loss of fat free mass is common in cancer patients. Body mass index (BMI) and weight loss are usually used in the diagnosis of malnutrition, but fail to detect underlying differences in fat free mass (FFM) and fat mass (FM) that can occur during cancer progression. Bioelectrical impedance analysis (BIA) might give a comprehensive picture of body composition and thereby be an important tool in early recognition of malnutrition. Disease however might violate the underlying assumptions of BIA. Objective: The primary objective of this thesis was to test the validity of bioelectrical impedance analysis (Seca mBCA 515), by investigating if it could accurately estimate fat mass (FM), fat free mass (FFM) and skeletal muscle mass (SMM) compared to dual-energy X-ray absorptiometry (Lunar iDXA), in cancer patients in a clinical setting. Further, the specific objectives were to investigate if validity varied in relation to treatment, diagnosis, BMI and fluid distribution (Extracellular water: Intracellular water (ECW:ICW) ratio). Methods: In this validation study, body composition of 69 eligible cancer patients at an ambulatory nutrition care clinic was assessed using Seca mBCA515 and iDXA. In addition nutritional status was assessed by Nutritional Risk Screening (NRS-2002), Patient Generated Subjective Global Assessment (PG-SGA), anthropometric measures and hand-grip strength. Results: No significant difference was found in estimated FM (kg) and FFM (kg) between DXA and BIA at the group level, with the differences corresponding to a mean percentage difference of 0.01% and 0.54%, respectively. At the individual level, the differences between DXA and BIA were <4 kg for both FM (kg) and FFM (kg) in approximately 95% of the patients. Systematic bias was found with higher discrepancies between the methods in the extreme ends of the FFM spectrum. SMM (kg) measured with Seca mBCA515 was underestimated with 64.2% and 50.9% in arms and legs, respectively compared to LST (kg) measured with iDXA. ECW:ICW ratio was a significant predictor of systematic bias in FFM (kg) and FM (kg). FFM (kg) was underestimated in patients with ECW expansion. Conclusion: At the group level, Seca mBCA515 was a valid tool for assessment of FM (kg) and FFM (kg) in the current cancer population. At the individual level differences were <10% of mean FFM (kg) which is considered a good agreement. Results from patients with ECW expansion should be interpreted with caution, as underestimation of FFM (kg) was seen. SMM (kg) measured by Seca mBCA515 is not comparable to LST measured with iDXA. | eng |