Title: The possibilities and limitation of our research for body composition of cancer cachectic patients with bioelectrical impedance analysis
Abstract:
Background & Aim: The prognostic factor of cancer cachectic population has been researched for a long time, however, we have not yet had outstanding one. Recently, researchers have focused on body composition measured by Bioelectrical Impedance Analysis(BIA) in which data has been collected by measuring the impedance of body water and cell membranes. Phase angle (PhA) calculated with reactance and resistance of cell membrane is a good tool to use when assessing the nutritional status and, especially, the promising marker for clinical prognosis of patients with cancer. The aim of this study was to evaluate the predictive utility of PhAs which and how are mediated by several BIA factors and other anthropometric parameters, such as calf circumference(CC) length, for the prognosis of patients with cancer cachexia.
Material and Methods: In total, 171 consecutive patients (both outpatients and inpatients) for whom the stage of cancer cachexia was determined from July 2019 to December 2022 in Mukaijima private Hospital, were included in this retrospective cohort study. Their mean age was 72.3 (standard deviation, 7.4) years; 99 were males and 72 females. Time-dependent Cox proportional-hazards regression (adjusted for age and sex) was performed to assess the following:
1) The association between potential mediators and mortality.
2) The association between five PhAs and statistically significant mediators from 1.
3) The association between the five PhAs and mortality. Finally, Kaplan-Meier survival curves were compared between two groups based on patients median baseline ratio of extracellular water (ECW) to total body water (TBW) using a log-rank test.
Results: The ECW/TBW ratio (hazard ratio [HR] per 1-interquartile range [IQR] increase: 2.87; 95% confidence interval [CI]: 1.46, 5.46; p<0.001) and skeletal muscle mass index (SMI; HR per 1-IQR increase: 0.67; 95% CI: 0.51-0.89; p=0.001) were associated with mortality. All five PhAs were associated with the ECW/TBW ratio (p<0.001). Before adjustment for the ECW/TBW ratio, all five PhAs were associated with mortality (p<0.001); after adjustment, only the PhAs of the left arm and the trunk were associated with mortality (p<0.05). The median survival times in the low ECW/TBW groups (370 days; 95% CI: 168, not calculated) was significantly longer than in the high ECW/TBW groups (101 days; 95% CI: 61, 219) (p<0.001). Conclusion Although PhA was associated with mortality, this association was largely mediated by the ECW/TBW ratio.
Keywords: Bioelectrical impedance analysis, body composition, phase angle, ECW/TBW.
