Date amended:
Statements of Principles
Current RMA Instruments
Reasonable Hypothesis SOP
17 of 2023
Balance of Probabilities SOP
18 of 2023
Changes from previous Instruments


ICD Coding

ICD-10-AM Codes: J41, J42, J43, J44

Brief description

This SOP covers: chronic bronchitis (with or without obstruction); emphysema; and persistent airflow limitation. The terminology in this field can be given different meanings in different settings and can be confusing.  There are a range of other lung diseases that can present in a similar way, that are not covered by this SOP.  Symptoms and clincial findings require careful evaluation and diagnosis can be difficult. 

Confirming the diagnosis

A diagnosis of chronic bronchitis requires evidence of chronic cough with sputum production.

A diagnosis of emphysema will generally be made based on spirometry showing persistent airflow limitation, or a high resolution CT lung scan showing the disease, or other specific lung function studies, reported by a respiratory physician.

Accurate diagnosis of persistent airflow limitation requires maximal effort post bronchodilator spirometry, with repeatable results obtained on calibrated equipment.  This generally means respiratory function testing undertaken at a respiratory laboratory. 

Note: persistent airflow limitation is not generally diagnosed as a separate condition if it is an integral manifestation of another diagnosed respiratory disease.  See further comments, below.

The relevant medical specialist is a respiratory physician.  A report froma respiratory physician should be obtained where possible to establish the correct diagnosis. 

Additional diagnoses covered by the SOP
  • Chronic airflow limitation
  • Chronic bronchitis
  • Chronic obstructive bronchitis
  • Chronic obstructive airways disease
  • Chronic obstructive lung disease
  • Chronic simple bronchitis
  • Emphysema
Conditions excluded from the SOP
  • Acute or recurrent bronchitis#
  • Asbestosis*
  • Asthma*
  • Bronchiectasis*
  • Bronchiolitis obliterans#
  • extrinsic allergic alveolitis/hypersensitivity pneumonitis*
  • fibrosing interstitial lung disease*
  • Emphysema that is localised or focal#
  • Hyperlucent lung syndrome#
  • isolated emphysematous bleb#
  • MacLeod’s syndrome#
  • Surgical emphysema#
  • Swyer-James syndrome#
  • Traumatic emphysema#

* another SOP applies  

# non-SOP condition

Clinical onset

The clinical onset depends on the type of disease. 

  • For chronic bronchitis, once the diagnosis is confirmed, the clinical onset will date from the start of the first period of time when the necessary cough (productive of sputum for 3 months, not due to another condition) was present.
  • For emphysema, clinical onset can be determined based on the first demonstration of the relevant pathological changes on (high resolution) CT scan of the lungs.  The onset can also be determined on clinical grounds based on shortness of breath and the first demonstration of a non-reversible obstructive pattern on spirometry (FEV1/FVC < 70%), or the first evidence of significant gas trapping on measurement of diffusing capacity (DLCO), provided these findings have been interpreted by a specialist physician as being attributable to emphysema (and not some other disease).
  • For persistent airflow limitation the clinical onset will be when (reliable) spirometry results first demonstrated the necessary, non-reversible pattern (FEV1/FVC < 70%). 
Clinical worsening

The normal course of chronic obstructive pulmonary disease (COPD) is generally for it to slowly worsen over time and for episodic exacerbations to occur.  Cessation of smoking can lead to an improvement in symptoms, particularly for chronic bronchitis.  Worsening can be demonstrated by an increase in symptoms, a decline in exercise tolerance, or a deterioration in test results (e.g. spirometry).  Whether there is deterioration over and above the normal course of the disease will be a matter for medical judgement.  Treatment may improve symptoms and can prevent or reduce exacerbations and prolong survival, but will generally not significantly alter the underlying pathology of the disease.

Further comments on diagnosis

Persistent airflow limitation most commonly arises from chronic inhalation of respiratory irritants, particularly tobacco smoke.  But irreversible airflow limitation can also be a feature of other diseases such as severe asthma.  In the setting where there is a history of asthma with reversible airflow limitation and there is also irreversible airflow limitation, with a FEV1/FVC of < 70%, then whether the irreversible component is assessed as being a manifestation of the asthma (and so covered by that diagnosis) or warranting a separate diagnosis of COPD, will be a matter for clinical judgement.  The same approach would apply for bronchiectasis and alpha-1 antitrypsin deficiency with persistent airflow limitation.