Abstract
Quadriceps strength relates to exercise capacity and prognosis in chronic obstructive pulmonary disease (COPD). We wanted to quantify the prevalence of quadriceps weakness in COPD and hypothesised that it would not be restricted to patients with severe airflow obstruction or dyspnoea.
Predicted quadriceps strength was calculated using a regression equation (incorporating age, sex, height and fat-free mass), based on measurements from 212 healthy subjects. The prevalence of weakness (defined as observed values 1.645 standardised residuals below predicted) was related to Global Initiative for Chronic Obstructive Lung Disease (GOLD) stage and Medical Research Council (MRC) dyspnoea score in two cohorts of stable COPD outpatients recruited from the UK (n = 240) and the Netherlands (n = 351).
32% and 33% of UK and Dutch COPD patients had quadriceps weakness. A significant proportion of patients in GOLD stages 1 and 2, or with an MRC dyspnoea score of 1 or 2, had quadriceps weakness (28 and 26%, respectively). These values rose to 38% in GOLD stage 4, and 43% in patients with an MRC Score of 4 or 5.
Quadriceps weakness was demonstrable in one-third of COPD patients attending hospital respiratory outpatient services. Quadriceps weakness exists in the absence of severe airflow obstruction or breathlessness.
Footnotes
Support Statement
J.M. Seymour was funded by the British Lung Foundation, and an unrestricted educational grant from GlaxoSmithKline administered by the Royal Brompton Hospital, London, UK. N.S. Hopkinson was funded by the Wellcome Trust UK and the ENIGMA in COPD Project (European Union). S.A. Natanek was funded by the Wellcome Trust UK and an unrestricted educational grant from GlaxoSmithKline. W.D-C. Man was funded by the National Institute for Health (UK) Research Clinician Scientist Programme. A. Jackson was funded by the Moulton Foundation. Part of this project was undertaken at the NIHR Biomedical Research Unit in Advanced Lung Disease at the Royal Brompton and Harefield NHS Foundation Trust and Imperial College London. M.I. Polkey’s salary was part-funded by the NIHR Biomedical Research Unit funding scheme. The views expressed in this publication are those of the authors and not necessarily those of the NHS, The National Institute for Health Research or the Department of Health.
Statement of Interest
Statements of interest for J.M. Seymour, S.A. Natanek and M.I. Polkey can be found at www.erj.ersjournals.com/misc/statements.dtl
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