title: The bioimpedance phase angle predicts low muscle strength, impaired quality of life, and increased mortality in old patients with cancer.
abstract: OBJECTIVE
  We investigated the impact of low phase angle (PhA) values on muscle strength, quality of life, symptom severity, and 1-year mortality in older cancer patients.
  
  
  METHODS
  Prospective study with 1-year follow-up.
  
  
  METHODS
  Cancer patients aged >60 years.
  
  
  METHODS
  PhA was derived from whole body impedance analysis. The fifth percentile of age-, sex-, and body mass index-stratified reference values were used as cut-off. Quality of life was determined with the European Organization of Research and Treatment in Cancer questionnaire, reflecting both several function scales and symptom severity. Muscle strength was assessed by hand grip strength, knee extension strength, and peak expiratory flow.
  
  
  RESULTS
  433 cancer patients, aged 60-95 years, were recruited. Patients with low PhA (n = 197) exhibited decreased muscle strength compared with patients with normal PhA (hand grip strength: 22 ± 8.6 vs 28.9 ± 8.9 kg, knee extension strength: 20.8 ± 11.8 vs 28.1 ± 14.9 kg, and peak expiratory flow: 301.1 ± 118 vs 401.7 ± 142.6 L/min, P < .001). Physical function, global health status, and role function from the European Organization of Research and Treatment in Cancer questionnaire were reduced, and most symptoms (fatigue, anorexia, pain, and dyspnea) increased in patients with low PhA (P < .001). In a risk-factor adjusted regression analysis, PhA emerged as independent predictor of physical function (ß:-0.538, P = .023), hand grip strength (ß:-4.684, P < .0001), knee extension strength (ß:-4.548, P = .035), and peak expiratory flow (ß:-66.836, P < .0001). Low PhA moreover predicted 1-year mortality in the Cox proportional hazards regression model, whereas grip strength was no longer significant.
  
  
  CONCLUSIONS
  PhA below the fifth reference percentile is highly predictive of decreased muscle strength, impaired quality of life, and increased mortality in old patients with cancer and should be evaluated in routine assessment.
authors.affiliation: Research Group on Geriatrics, Charite University Medicine Berlin, Berlin, Germany. Electronic address: kristina.norman@charite.de.
authors.forename: Kristina
authors.initials: K
authors.lastname: Norman
authors.affiliation: Department of Internal Medicine and Geriatrics, St.-Marien-Hospital Borken, Borken, Germany; Institute for Biomedicine of Aging (IBA), Friedrich-Alexander-University Erlangen-Nürnberg, Nürnberg, Germany.
authors.forename: Rainer
authors.initials: R
authors.lastname: Wirth
authors.affiliation: Charite Comprehensive Cancer Center, Charite University Medicine Berlin, Berlin, Germany; Department of Hepatology and Gastroenterology, Charite University Medicine Berlin, Berlin, Germany.
authors.forename: Maxi
authors.initials: M
authors.lastname: Neubauer
authors.affiliation: Research Group on Geriatrics, Charite University Medicine Berlin, Berlin, Germany.
authors.forename: Rahel
authors.initials: R
authors.lastname: Eckardt
authors.affiliation: Research Group on Geriatrics, Charite University Medicine Berlin, Berlin, Germany; Department of Hepatology and Gastroenterology, Charite University Medicine Berlin, Berlin, Germany.
authors.forename: Nicole
authors.initials: N
authors.lastname: Stobäus
mesh_terms: D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D002423:Cause of Death; D015331:Cohort Studies; D016001:Confidence Intervals; D017097:Electric Impedance; D005260:Female; D015577:Geriatric Assessment / Q000379:methods*; D005858:Germany; D006801:Humans; D008297:Male; D008875:Middle Aged; D053580:Muscle Strength / Q000502:physiology*; D009369:Neoplasms / Q000401:mortality / Q000503:physiopathology* / Q000523:psychology*; D010809:Physical Fitness / Q000502:physiology; D011237:Predictive Value of Tests; D016016:Proportional Hazards Models; D011446:Prospective Studies; D011788:Quality of Life; D018570:Risk Assessment; D012737:Sex Factors; D018434:Sickness Impact Profile; D016019:Survival Analysis
keywords: Phase angle; cancer; functional status; mortality; muscle strength; quality of life