title: Fat-Free Mass Index for Evaluating the Nutritional Status and Disease Severity in COPD.
abstract: BACKGROUND
  Despite the high prevalence of weight loss in subjects with COPD, the 2011 COPD management guidelines do not include an index measuring nutritional status. Fat-free mass index (FFMI) can accurately determine the nutritional status of subjects and may be closely correlated with COPD severity. We aimed to determine the nutritional status evaluated by FFMI according to the 2011 Global Initiative for Chronic Obstructive Lung Disease (GOLD) levels in stable subjects with COPD and the association between nutritional status and respiratory symptoms, exercise capacity, and respiratory muscle function.
  
  
  METHODS
  We included 235 stable subjects with COPD in this cross-sectional study. All of the subjects were divided into the 2011 GOLD Groups A, B, C, and D. FFMI (measured by bioelectrical impedance), spirometry (FEV1, percent-of-predicted FEV1, and FEV1/FVC), respiratory muscle function (peak inspiratory and peak expiratory pressures), exercise capacity (6-min walk distance), and dyspnea severity (Modified Medical Research Council dyspnea scale) were measured and compared between the GOLD groups.
  
  
  RESULTS
  Malnutrition was identified in 48.5% of subjects and most prevalent in Group D (Group A: 41%, Group B: 41%, Group C: 31%, and Group D: 62%). FFMI was significantly lower in Group D (P < .001), with both sexes considered malnourished. Low FFMI significantly correlated with frequent exacerbation, older age, decreased pulmonary function, 6-min walk distance, peak inspiratory pressure, and worsened dyspnea. FFMI was significantly lower in the emphysema-dominant phenotype and mixed phenotype compared with the normal phenotype and airway-dominant phenotype. A stepwise multiple linear regression analysis identified peak inspiratory pressures and older age as independent predictors of FFMI.
  
  
  CONCLUSIONS
  Malnutrition is highly prevalent in all COPD groups, particularly in Group D subjects, who warrant special attention for nutritional intervention and pulmonary rehabilitation. FFMI significantly correlated with exercise capacity, dyspnea, respiratory muscle function, and pulmonary function and may be a useful predictor of COPD severity.
authors.affiliation: Department of Respiratory Medicine, Zhujiang Hospital, Southern Medical University, Guangzhou 510282, China.
authors.forename: Yuwen
authors.initials: Y
authors.lastname: Luo
authors.affiliation: State Key Laboratory of Respiratory Disease, Guangzhou Institute of Respiratory Disease, Guangzhou Medical University, Guangzhou 510120, China.
authors.forename: Luqian
authors.initials: L
authors.lastname: Zhou
authors.affiliation: Department of Respiratory Medicine, Zhujiang Hospital, Southern Medical University, Guangzhou 510282, China.
authors.forename: Yun
authors.initials: Y
authors.lastname: Li
authors.affiliation: Department of Respiratory Medicine, Zhujiang Hospital, Southern Medical University, Guangzhou 510282, China.
authors.forename: Songwen
authors.initials: S
authors.lastname: Guo
authors.affiliation: Department of Respiratory Medicine, Zhujiang Hospital, Southern Medical University, Guangzhou 510282, China.
authors.forename: Xiuxia
authors.initials: X
authors.lastname: Li
authors.affiliation: Department of Respiratory Medicine, Zhujiang Hospital, Southern Medical University, Guangzhou 510282, China.
authors.forename: Jingjing
authors.initials: J
authors.lastname: Zheng
authors.affiliation: Department of Respiratory Medicine, Zhujiang Hospital, Southern Medical University, Guangzhou 510282, China.
authors.forename: Zhe
authors.initials: Z
authors.lastname: Zhu
authors.affiliation: Department of Respiratory Medicine, Zhujiang Hospital, Southern Medical University, Guangzhou 510282, China.
authors.forename: Yitai
authors.initials: Y
authors.lastname: Chen
authors.affiliation: Department of Respiratory Medicine, Zhujiang Hospital, Southern Medical University, Guangzhou 510282, China.
authors.forename: Yuxia
authors.initials: Y
authors.lastname: Huang
authors.affiliation: Department of Respiratory Diseases, SUN Yat-sen Memorial Hospital, SUN Yat-sen University, Guangzhou 510120, China. chen_xin1020@hotmail.com gzchenrui@163.com.
authors.forename: Rui
authors.initials: R
authors.lastname: Chen
authors.affiliation: Department of Respiratory Medicine, Zhujiang Hospital, Southern Medical University, Guangzhou 510282, China. chen_xin1020@hotmail.com gzchenrui@163.com.
authors.forename: Xin
authors.initials: X
authors.lastname: Chen
mesh_terms: D000368:Aged; D015992:Body Mass Index; D003430:Cross-Sectional Studies; D004417:Dyspnea; D017097:Electric Impedance; D017079:Exercise Tolerance / Q000502:physiology; D005260:Female; D006801:Humans; D008168:Lung / Q000503:physiopathology; D008297:Male; D044342:Malnutrition / Q000453:epidemiology* / Q000209:etiology; D008875:Middle Aged; D009752:Nutritional Status; D015995:Prevalence; D029424:Pulmonary Disease, Chronic Obstructive / Q000150:complications / Q000503:physiopathology*; D012132:Respiratory Muscles / Q000503:physiopathology; D012720:Severity of Illness Index; D013147:Spirometry; D014057:Tomography, X-Ray Computed
keywords: chronic obstructive pulmonary disease; epidemiology; free fat mass index; malnutrition; prognosis; pulmonary function