Intended for healthcare professionals

Practice Change

Do not diagnose or routinely treat asthma or chronic obstructive pulmonary disease without pulmonary function testing

BMJ 2023; 380 doi: (Published 20 March 2023) Cite this as: BMJ 2023;380:e072834
  1. Samir Gupta, associate professor1 2,
  2. Guylène Thériault, physicianship director3
  1. 1Li Ka Shing Knowledge Institute of St. Michael’s Hospital, Unity Health, Toronto, Canada
  2. 2Division of Respirology, Department of Medicine, University of Toronto, Toronto, Canada
  3. 3Campus Outaouais McGill University, Quebec, Canada
  1. Correspondence to S Gupta samir.gupta{at}

What you need to know

  • More than a third of diagnoses of asthma or COPD made on clinical grounds alone are incorrect

  • A clinical diagnosis of a chronic airways disease without objective testing may harm patients by exposing them to unnecessary medications, while missing their actual diagnosis

  • Given the barriers to objective testing of lung function, including timely test access, it may be reasonable to treat symptoms before a formal diagnosis is made, while arranging for formal tests

Asthma and chronic obstructive pulmonary disease (COPD) are among the most common chronic diseases seen in primary care, affecting 262 million and 212 million individuals worldwide, respectively.1 Respiratory complaints are also the most common reason for a visit to primary care,2 and providers often ascribe lower respiratory symptoms (particularly when recurring or chronic) to asthma or COPD, and initiate treatment based on a clinical diagnosis. However, prospective studies have shown that symptoms elicited during clinical history when asthma or COPD are suspected do not accurately predict disease in real world settings.3 Similarly, features of physical examinations, such as wheeze, are non-specific, and neither individual nor combined physical examination findings have been found to reliably predict obstructive airways disease.4

Evidence from existing studies suggests that more than half of patients who receive a diagnosis of asthma or COPD do not have objective lung function tests performed. In Canadian population based studies using administrative databases and applying validated case definitions, 43% and 36% of patients with a new diagnostic label of asthma5 and COPD,6 respectively, had received pulmonary function testing within one year of their diagnosis. A US administrative database study applied the same methods and found a comparable number (48%) for asthma.7 A smaller Italian study found that 55% and 56% of patients seen in a spirometry laboratory who self-reported a …

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