What are the key diagnostic criteria for identifying work-related asthma in a patient presenting with respiratory symptoms?

Key diagnostic criteria for identifying work-related asthma in a patient presenting with respiratory symptoms include:

• Taking a detailed clinical history focusing on the temporal relationship between symptoms and work exposure, specifically asking if symptoms are the same, better, or worse on days away from work, during holidays, weekends, or longer breaks from work. This helps identify a possible occupational component in adult-onset, poorly controlled, or recurrent asthma ¹.
• Confirming asthma diagnosis with objective tests such as spirometry showing variable airflow obstruction, bronchodilator reversibility, or peak expiratory flow (PEF) variability of 20% or more measured twice daily over 2 weeks ¹.
• Referral to an occupational asthma specialist for further assessment and confirmation, including consideration of specific inhalation challenge tests or serial PEF monitoring at and away from work ¹; (Baur et al., 2012).
• Excluding alternative diagnoses through clinical examination and investigations, as work-related asthma can mimic or coexist with other respiratory conditions ¹; (Bardana, 1995).
• Supporting investigations may include skin prick testing or measurement of specific IgE to workplace allergens, blood eosinophil counts, and fractional exhaled nitric oxide (FeNO) to identify allergic sensitisation and airway inflammation consistent with asthma ¹; (Arnaiz and Kaufman, 2002).

In summary, the diagnosis of work-related asthma relies on a combination of a suggestive clinical history linking symptoms to workplace exposure, objective confirmation of asthma, exclusion of other diagnoses, and specialist referral for occupational assessment and testing.