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Updated: The value of tests in respiratory disease

Posted on: 5 Sep 2019

This module was originally published in July 2017, and has been updated in September 2019.

Module summary

This module will review the use of medical tests in the diagnosis of respiratory diseases.

Learning objectives

After completing the module, you should:

  • know the advantages and disadvantages of common respiratory tests and their role in the diagnosis of respiratory conditions
  • be aware of key barriers and considerations in selecting and performing tests
  • understand the roles of medical tests in supporting or excluding a diagnosis
  • appreciate the need for appropriate training of staff who perform and interpret respiratory tests.


There is a need for earlier and more accurate diagnosis of respiratory conditions. Studies have shown that up to 80% of chronic obstructive pulmonary disease (COPD) cases remain undiagnosed until the disease is in its advanced stages.1 In addition, misdiagnosis of respiratory conditions occurs frequently; a study found that up to 25% of patients aged over 40 years labelled as having asthma actually had COPD.2 Indeed, while asthma has been underdiagnosed in the past, there is evidence that it may be overdiagnosed now.3,4

The incorrect diagnosis of respiratory conditions has consequences for both the patient and healthcare system. These include increased treatment costs, side effects from inappropriate (and ineffective) medications and unnecessary patient distress.4,5

Previously published diagnostic guidelines from the International Primary Care Respiratory Group (IPCRG) have referred to the ‘unique challenges’ in diagnosing respiratory conditions. Shared pathologies and symptoms common to different conditions, the intermittent presence of symptoms and the variable clinical presentations of certain conditions can complicate diagnosis.6

Clinical guidelines (European Respiratory Society [ERS],7 National Institute for Health and Care Excellence [NICE],8,9 Global Initiative for Chronic Obstructive Lung Disease [GOLD] strategy document10, British Thoracic Society/Scottish Intercollegiate Guidelines Network [BTS/SIGN]11) provide synopses of the diagnostic assessments required to establish and confirm a diagnosis of COPD or asthma. Respiratory tests are a powerful tool for confirming a diagnosis; however, they often do not ‘automatically’ provide a diagnosis. There are factors which must be taken into account if these tests are to provide maximum value in aiding diagnosis.


ARTP Association for Respiratory Technology and Physiology GP General practitioner
BMI Body mass index ICS Inhaled corticosteroid
BTS British Thoracic Society IPCRG International Primary Care Respiratory Group
CAT COPD Assessment Test LABA Long-acting beta agonist
COPD Chronic obstructive pulmonary disease LAMA Long-acting muscarinic antagonist
CT Computed tomography LVEF Left ventricular ejection fraction
ECG Electrocardiogram MRI Magnetic resonance imaging
ERS European Respiratory Society NICE National Institute for Health and Care Excellence
FBC Full blood count PEFR Peak expiratory flow rate
FeNO Forced exhaled nitric oxide or fraction of exhaled nitric oxide PET Positron emission tomography
FEV1 Forced expiratory volume in 1st second SABA Short-acting beta agonist
FVC Forced vital capacity SAMA Short-acting muscarinic antagonist
GOLD Global Initiative for Chronic Obstructive Lung Disease SIGN Scottish Intercollegiate Guidelines Network


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The Primary Care Respiratory Academy has been developed and is produced by Cogora, the publisher of Pulse, Nursing in Practice, Healthcare Leader, Management in Practice and The Pharmacist working in partnership with PCRS.

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