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The boundaries of mild chronic obstructive pulmonary disease (COPD): design of the searching clinical COPD onset (SOON) study
  1. Gonzalo Labarca1,2,
  2. Andrea Bustamante3,
  3. Gonzalo Valdivia4,
  4. Rodrigo Díaz3,
  5. Álvaro Huete5,
  6. Paul Mac Nab6,
  7. Laura Mendoza7,
  8. Jaime Leppe8,
  9. Carmen Lisboa3,
  10. Fernando Saldías3,
  11. Orlando Díaz3,9
  1. 1 Faculty of Medicine, Universidad San Sebastián, Concepción, Concepción, Chile
  2. 2 Division of Internal Medicine, Complejo Asistencial Víctor Ríos Ruiz, Los Ángeles, Chile
  3. 3 Department of Pulmonary Diseases, Faculty of Medicine, Pontifical Catholic University of Chile, Santiago, Chile
  4. 4 Department of Public Health, Faculty of Medicine, Pontifical Catholic University of Chile, Santiago, Chile
  5. 5 Department Radiology, Faculty of Medicine, Pontifical Catholic University of Chile, Santiago, Chile
  6. 6 Department of Cardiovascular Diseases, Faculty of Medicine, Pontifical Catholic University of Chile, Santiago, Chile
  7. 7 Section of Pulmonary Medicine, Department of Medicine, Universidad de Chile, Santiago, Chile
  8. 8 School of Physical Therapy,​ ​Facultad de Medicina​ ​Clínica Alemana, Universidad del Desarrollo, Santiago, Chile
  9. 9 Department of Critical Care, Faculty of Medicine, Pontifical Catholic University of Chile, Santiago, Chile
  1. Correspondence to Dr Orlando Díaz; odiazpat{at}gmail.com

Abstract

Introduction Clinical onset of chronic obstructive pulmonary disease (COPD) is the point at which the disease is first identifiable by physicians. It is a poorly defined stage which seems to include both mild spirometric and non-spirometric disease, and could be described as early grade COPD, for practical purposes. While dyspnoea; chronic bronchitis and CT imaging evidence of emphysema and airway disease may be present very early, the lone significance of dyspnoea, the most relevant symptom in COPD in identifying these individuals, has been scarcely assessed.

The Searching Clinical COPD Onset (SOON) Study was designed primarily to detect clinical, physiological and structural differences between dyspnoeic and non-dyspnoeic individuals with early grade COPD. It is hypothesised that presence of dyspnoea in early disease may identify a subtype of individuals with reduced exercise capacity, notwithstanding of their spirometry results. In addition, dyspnoeic individuals will share worse quality of life, lower physical activity, greater lung hyperinflation greater emphysema and airway thickness and reduced peripheral muscle mass than their non-dyspnoeic counterpart.

Methods and analysis SOON is a monocentric study, with a cross sectional design aimed at obtaining representative samples of current or ex-smoker-adults aged ≥45 and ≤80 years. Two hundred and forty participants will be enrolled into four strata, according to normal spirometry or mild spirometric obstruction and presence or not of dyspnoea modified Medical Research Council score ≥1. The primary outcome will be the difference between dyspnoeic and non-dyspnoeic individuals on the 6-min walk test performance, regardless of their spirometry results. To account for the confounding effect of heart failure on dyspnoea, stress echocardiography will be also performed. Secondary outcomes will include clinical (quality of life, physical activity), physiological (exercise testing) and structural characteristics (emphysema, airway disease and peripheral muscle mass by CT imaging).

Ethics and dissemination The Institutional Ethics Committee from Pontificia Universidad Católica de Chile has approved the study protocol and signed informed consent will be obtained from all participants. The findings of the trial will be disseminated through relevant peer-reviewed journals and international conference presentations.

Trial registration number NCT03026439.

  • general medicine (see internal medicine)
  • thoracic medicine
  • adult thoracic medicine
  • chronic airways disease
  • emphysema

This is an Open Access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/

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Footnotes

  • Contributors OD: Mentor, conception and design of the study; recruitment of patients; data collection; analysis and interpretation and drafting the manuscript for important intellectual content, register in clinical trials and correspondence author. GL: Conception and design of the study; recruitment of patients; analysis and interpretation and drafting the manuscript for important intellectual content. AB: Conception and design of the study; recruitment of patients; drafting the manuscript for important intellectual content. CL: Analysis and interpretation and drafting the manuscript for important intellectual content. JL: Recruitment of patients; data analysis and interpretation. RD: Data collection; data analysis and interpretation. FS: Conception and design of the study; recruitment of patients; analysis and interpretation and drafting the manuscript for important intellectual content. AH: Conception and design of the study; data analysis and interpretation. PMN: Conception and design of the study; data collection; data analysis and interpretation. GV: Conception and design of the study; analysis and interpretation and drafting the manuscript for important intellectual content. LM: Recruitment of patients; data collection; drafting the manuscript for important intellectual content.

  • Funding Grant by National Fund for Scientific & Technological Development (FONDECYT) number # 1141108.

  • Competing interests None declared.

  • Patient consent Obtained.

  • Ethics approval Pontificia Universidad Catolica de Chile.

  • Provenance and peer review Not commissioned; externally peer reviewed.

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