Bioelectrical impedance phase angle relates to function, disease severity and prognosis in stable chronic obstructive pulmonary disease. Issue 6 (December 2015)

• Record Type: Journal Article
• Authors: Maddocks, Matthew; Kon, Samantha S.C.; Jones, Sarah E.; Canavan, Jane L.; Nolan, Claire M.; Higginson, Irene J.; Gao, Wei; Polkey, Michael I.; Man, William D.-C.
• Is Part Of: Clinical nutrition. Volume 34:Issue 6(2015:Dec.)
• Page Start: 1245
• Page End: 1250
• Publication Date: 2015-12
• Subjects: Body composition -- Bioelectrical impedance analysis -- Chronic obstructive pulmonary disease -- Fat-free mass -- Phase angle; ADO age dyspnea obstruction -- BIA bioelectrical impedance analysis -- BMI body mass index -- iBODE body mass index, obstruction, dyspnea, exercise capacity index -- COPD chronic obstructive pulmonary disease -- CAT COPD assessment test -- FFM fat-free mass (FFM) -- FFMI fat-free mass index -- GOLD global initiative for chronic obstructive lung disease -- MRC Medical Research Council -- QMVC quadriceps maximum voluntary contraction -- 4MGS 4-m gait speed -- 5STS 5 sit-to-stand -- ISW incremental shuttle walk; Critically ill -- Nutrition -- Periodicals; Diet therapy -- Periodicals; Parenteral feeding -- Periodicals; Enteral feeding -- Periodicals; Enteral Nutrition -- Periodicals; Parenteral Nutrition -- Periodicals; Metabolism -- Periodicals; Diétothérapie -- Périodiques; Alimentation parentérale -- Périodiques; Alimentation entérale -- Périodiques; Nutrition -- Périodiques; Diet therapy; Enteral feeding; Nutrition; Parenteral feeding; Electronic journals; Periodicals; Electronic journals; 615.854
• DOI: 10.1016/j.clnu.2014.12.020
• Languages: English
• ISSNs: 0261-5614

Abstract

Summary: Background & aims: Bioelectrical impedance analysis (BIA) provides a simple method to assess changes in body composition. Raw BIA variables such as phase angle provide direct information on cellular mass and integrity, without the assumptions inherent in estimating body compartments, e.g. fat-free mass (FFM). Phase angle is a strong functional and prognostic marker in many disease states, but data in COPD are lacking. Our aims were to describe the measurement of phase angle in patients with stable COPD and determine the construct and discriminate validity of phase angle by assessing its relationship with established markers of function, disease severity and prognosis. Methods: 502 outpatients with stable COPD were studied. Phase angle and FFM by BIA, quadriceps strength (QMVC), 4-m gait speed (4MGS), 5 sit-to-stand time (5STS), incremental shuttle walk (ISW), and composite prognostic indices (ADO, iBODE) were measured. Patients were stratified into normal and low phase angle and FFM index. Results: Phase angle correlated positively with FFM and functional outcomes (r = 0.35–0.66, p < 0.001) and negatively with prognostic indices (r = −0.35 to −0.48, p < 0.001). In regression models, phase angle was independently associated with ISW, ADO and iBODE whereas FFM was removed. One hundred and seventy patients (33.9% [95% CI, 29.9–38.1]) had a low phase angle. Phenotypic characteristics included lower QMVC, ISW, and 4MGS, higher 5STS, ADO and iBODE scores, and more exacerbations and hospital days in past year. The proportion of patients to have died was significantly higher in patients with low phase angle compared to those with normal phase angle (8.2% versus 3.6%, p = 0.02). Conclusion: Phase angle relates to markers of function, disease severity and prognosis in patients with COPD. As a directly measured variable, phase angle offers more useful information than fat-free mass indices.