Prospective metrological validation of multifrequency bioelectrical impedance analysis against volumetric imaging to identify sarcopenia in head and neck cancer patients undergoing radiation therapy

ImportanceDepleted skeletal muscle mass (sarcopenia) is associated with decreased survival and cancer control in head and neck cancer patients treated with radiotherapy. There is a need for validated measures of body composition that can be implemented in routine clinical workflow.ObjectiveTo validate the use of bioelectrical impedance analysis (BIA) for body composition analysis and diagnosis of sarcopenia in head and neck cancer patients.DesignIn this prospective observational cohort study, baseline 50 patients with head and neck cancer undergoing radiation therapy (RT) were enrolled between February 2016 and March 2017. Baseline BIA measures of skeletal muscle (SM) mass, fat-free mass (FMM), and fat mass (FM) were compared to CT-based estimates of body composition using linear regression. Sex-specific BIA-derived thresholds for sarcopenia were defined by the maximum Youden Index on receiver operator characteristic (ROC) curves of BIA against CT-defined sarcopenia. Changes in body composition across treatment were compared against changes in body weight using linear regression.ParticipantsIn total, 50 patients with pathologically confirmed stage I to IVB non-metastatic head and neck cancer treated with definitive radiation therapy were enrolled.SettingSingle academic referral center.Main Outcome and MeasureThe primary outcome was relative agreement between baseline lean body mass and fat body mass predicted from BIA measurement and CT imaging.ResultsOf the 48 evaluable patients 16 (33.3%) were sarcopenic at baseline based on CT analysis. BIA measures of body composition were strongly correlated with CT measures: SM mass (r = 0.97; R2 = 0.94; p < 0.0001), FFM (r = 0.97; R2 = 0.94; p < 0.0001) and FM (r = 0.95; R2 = 0.90; p < 0.0001). Relationship with normalized indices of SM mass, FFM, and FM was similar between BIA and CT, but not BIA and body mass index (BMI). Patients lost a mean of 5.7 ± 5.8 kg during treatment, of which 1.5 ± 1.9 kg was SM, 2.6 ± 3.3 kg was FFM, and 2.2 ± 2.6 kg was FM. Eight additional patients developed sarcopenia by the end of RT.ConclusionsBIA provides accurate estimates of body composition in head and neck cancer patients. Implementation of BIA in clinical practice may identify patients with sarcopenia.Trial RegistrationClinicalTrials.gov identifier: NCT02615275