Dr Christopher Barber Edit

The BTS Clinical Statement on Occupational Asthma

Tuesday, March 29, 2022

Respiratory Futures spoke to Dr Chris Barber, the Chair of the BTS group that developed the latest Clinical Statement on Occupational Asthma about the importance of this guidance.

What was the driver behind the development of this Clinical Statement?

Asthma is a very common condition in the UK, with many healthcare workers in primary and secondary care regularly involved in caring for these patients. In around 1 in 6 cases, adult-onset asthma is caused by a patient’s work, but unfortunately this link is often missed leading to delayed diagnosis. The aim of this Clinical Statement is to raise awareness of this condition and provide simple clinical practice points (based on expert opinion) to try to improve patient outcomes.

What is Occupational Asthma?

Occupational Asthma refers to asthma that has been caused by exposure to something in the workplace; it can be categorised into allergic Occupational Asthma due to sensitisation and irritant-induced asthma, depending on the underlying mechanism responsible. The main focus of the Clinical Statement relates to the allergic type, which is responsible for approximately 90% of cases. There are around 400 reported causes (known as “asthmagens” or “sensitisers”), which are mostly high molecular weight proteins (e.g., wheat flour) or low molecular weight reactive chemicals (e.g., diisocyanates in car spray paint). 

Although it is likely that individual susceptibility plays a key role in allergic Occupational Asthma, the most important risk factor for developing the condition is the level of exposure to the cause.  

Why is important to prevent and manage Occupational Asthma?

Occupational Asthma is largely preventable, and legislation requires that workplaces keep exposures to known asthmagens “as low as reasonably practicable”. Despite this, some cases of Occupational Asthma still occur, and health surveillance in the workplace, usually with an annual questionnaire and spirometry, is important to identify cases as early as possible.

Being in work is important for a number of reasons, not just to provide a source of income, but also because it can provide people with purpose, social interaction, structure and identity. Unfortunately, for many patients, the diagnosis of allergic Occupational Asthma adversely affects both their health and employment, with many having to move to lower paid jobs, or leave work altogether; not surprisingly anxiety and depression are common in this group of patients.

What does the Clinical Statement cover?

We mainly focused on diagnosis and management of the disease, but we have also included some background information on workplace health surveillance and prognosis. For completeness, a number of appendices also provide additional information to cover irritant induced asthma, legislation and guidance for workplace respiratory disease, the differential diagnosis of Occupational Asthma and audit criteria for primary and specialist care settings.

Why is diagnosing Occupational Asthma early crucial?

If spotted early enough, Occupational Asthma can effectively be cured, if workplace adaptations can be made that completely prevent further exposure to the cause. In most cases however, the reality is very different, as delays in diagnosis of several years, mean that most patients require asthma treatment for the rest of their lives, with 1 in 6 developing severe asthma. Although diagnostic delays may result from workers being concerned about the risk of unemployment, in many cases they are caused by missed opportunities to ask simple screening questions in primary and secondary care; the Clinical Statement highlights this problem area and provides healthcare workers with clear guidance.

Making a diagnosis of Occupational Asthma can have important repercussions not just on the individual affected, but also on their co-workers and employer – many patients with work-related symptoms do not have Occupational Asthma, and excluding the condition is just as important as it helps keep patients safely in work.

There is no single test for Occupational Asthma, but a diagnosis can usually be reached using a combination of careful history-taking, and the results of objective immunological and/or physiological tests. This area requires specialist training and experience, and the Clinical Statement promotes direct referral, where possible, to a centre with an occupational lung disease outpatient service. Early referral is very important, as it may be more difficult to reach a diagnosis once patients have been commenced on maintenance asthma treatment, and/or workplace adaptations have already been made.   

What treatment options are there for Occupational Asthma?

In terms of the pharmacological management of the disease, Occupational Asthma is treated in the same way as asthma unrelated to work and should follow national guidelines. Healthcare workers also need to be aware that patients with Occupational Asthma commonly have other co-existing conditions that needs to be recognised and treated separately, particularly allergic rhinitis, breathing pattern disorders, inducible laryngeal obstruction, anxiety, and depression.

The management of Occupational Asthma goes beyond treatment with medication, and clinicians have a key role in educating patients about the likely long term health outcomes if workplace exposure to the cause continues.  What makes the management of Occupational Asthma an area that requires specialist input, is the need to develop a personalised management plan that strikes the best possible balance between long term health and employment outcomes for each individual patient; this also needs to be flexible enough to change with the disease over time. In some cases, this may be very straightforward, whereas in others it requires repeated negotiations between the patient, the clinician, and the employer.

Another key element of management is to provide patients with accurate advice about eligibility for specific government benefits (particularly Industrial Injuries Disablement Benefit), and civil compensation.  Regular specialist follow up is advisable for all patients who continue to work in an environment where there is potential exposure to the cause; patients with severe asthma may also need input from specialist asthma services for consideration of biologic therapy.

What would your take home messages be from the Clinical Statement?

Occupational Asthma is much more common than you think and can have a devastating personal impact on your patient.

Screening questions are quick and easy – but these are often overlooked.

Early diagnosis is key to a good outcome - refer cases directly to a specialist as soon as possible.