title: Phenotypic characteristics associated with reduced short physical performance battery score in COPD.
abstract: BACKGROUND
  The Short Physical Performance Battery (SPPB) is commonly used in gerontology, but its determinants have not been previously evaluated in COPD. In particular, it is unknown whether pulmonary aspects of COPD would limit the value of SPPB as an assessment tool of lower limb function.
  
  
  METHODS
  In 109 patients with COPD, we measured SPPB score, spirometry, 6-min walk distance, quadriceps strength, rectus femoris cross-sectional area, fat-free mass, physical activity, health status, and Medical Research Council dyspnea score. In a subset of 31 patients with COPD, a vastus lateralis biopsy was performed, and the biopsy specimen was examined to evaluate the structural muscle characteristics associated with SPPB score. The phenotypic characteristics of patients stratified according to SPPB were determined.
  
  
  RESULTS
  Quadriceps strength and 6-min walk distance were the only independent predictors of SPPB score in a multivariate regression model. Furthermore, while age, dyspnea, and health status were also univariate predictors of SPPB score, FEV 1 was not. Stratification by reduced SPPB score identified patients with locomotor muscle atrophy and increasing impairment in strength, exercise capacity, and daily physical activity. Patients with mild or major impairment defined as an SPPB score < 10 had a higher proportion of type 2 fibers (71% [14] vs 58% [15], P = .04).
  
  
  CONCLUSIONS
  The SPPB is a valid and simple assessment tool that may detect a phenotype with functional impairment, loss of muscle mass, and structural muscle abnormality in stable patients with COPD.
authors: NIHR Respiratory Biomedical Research Unit, Royal Brompton & Harefield NHS Foundation Trust and Imperial College London, London, England.
authors: Mehul S
authors: MS
authors: Patel
authors: NIHR Respiratory Biomedical Research Unit, Royal Brompton & Harefield NHS Foundation Trust and Imperial College London, London, England.
authors: Divya
authors: D
authors: Mohan
authors: Respiratory, Inflammation, and Autoimmune Diseases, AstraZeneca, Mölndal, Sweden.
authors: Yvonne M
authors: YM
authors: Andersson
authors: NIHR Respiratory Biomedical Research Unit, Royal Brompton & Harefield NHS Foundation Trust and Imperial College London, London, England.
authors: Manuel
authors: M
authors: Baz
authors: NIHR Respiratory Biomedical Research Unit, Royal Brompton & Harefield NHS Foundation Trust and Imperial College London, London, England; Harefield Pulmonary Rehabilitation Unit, London, England.
authors: S C
authors: SC
authors: Samantha Kon
authors: NIHR Respiratory Biomedical Research Unit, Royal Brompton & Harefield NHS Foundation Trust and Imperial College London, London, England; Harefield Pulmonary Rehabilitation Unit, London, England.
authors: Jane L
authors: JL
authors: Canavan
authors: Respiratory, Inflammation, and Autoimmune Diseases, AstraZeneca, Mölndal, Sweden.
authors: Sonya G
authors: SG
authors: Jackson
authors: Harefield Pulmonary Rehabilitation Unit, London, England.
authors: Amy L
authors: AL
authors: Clark
authors: NIHR Respiratory Biomedical Research Unit, Royal Brompton & Harefield NHS Foundation Trust and Imperial College London, London, England.
authors: Nicholas S
authors: NS
authors: Hopkinson
authors: NIHR Respiratory Biomedical Research Unit, Royal Brompton & Harefield NHS Foundation Trust and Imperial College London, London, England.
authors: Samantha A
authors: SA
authors: Natanek
authors: Department of Molecular Medicine, Imperial College London, London, England.
authors: Paul R
authors: PR
authors: Kemp
authors: Respiratory, Inflammation, and Autoimmune Diseases, AstraZeneca, Mölndal, Sweden.
authors: Piet L B
authors: PLB
authors: Bruijnzeel
authors: Harefield Pulmonary Rehabilitation Unit, London, England.
authors: William D-C
authors: WD
authors: Man
authors: NIHR Respiratory Biomedical Research Unit, Royal Brompton & Harefield NHS Foundation Trust and Imperial College London, London, England. Electronic address: m.polkey@rbht.nhs.uk.
authors: Michael I
authors: MI
authors: Polkey
mesh_terms: D000203:Activities of Daily Living; D000368:Aged; D005080:Exercise Test; D005260:Female; D005500:Follow-Up Studies; D006304:Health Status; D006801:Humans; D008297:Male; D008875:Middle Aged; D009043:Motor Activity / Q000502:physiology*; D053580:Muscle Strength / Q000502:physiology*; D018482:Muscle, Skeletal / Q000503:physiopathology*; D010641:Phenotype; D011379:Prognosis; D011446:Prospective Studies; D029424:Pulmonary Disease, Chronic Obstructive / Q000175:diagnosis / Q000503:physiopathology*; D012720:Severity of Illness Index; D013147:Spirometry; D016138:Walking