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Suspected sensitiser-induced occupational asthma — SCE Respiratory MCQ

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HardAsthma GuidelinesSuspected sensitiser-induced occupational asthmaSCE Respiratory

A 39-year-old vehicle refinisher has an 8-month history of episodic wheeze, cough and chest tightness. Symptoms worsen towards the end of shifts spraying two-component polyurethane paint, improve after 3 to 4 days away from work and disappeared during a 2-week holiday, recurring on his first shift back. He had no childhood asthma and recalls no single high-level irritant exposure. Spirometry demonstrates airflow obstruction with an FEV1 increase of 330 mL and 15% after bronchodilator; FeNO is 68 ppb. He has used low-dose budesonide/formoterol maintenance and reliever therapy for 3 months, with verified adherence and unchanged maintenance dosing for 6 weeks. He is clinically stable, remains in the same role and wants the diagnosis clarified before making employment decisions. Which is the most appropriate next diagnostic plan?

Educational content. Not a substitute for clinical judgement or local policy.

Reveal the answer and explanation

Correct answer: A — Refer promptly and record peak flow at least four times daily for at least 3 weeks across work and rest periods, documenting exposures and medication use.

Explanation lettering: C = shown as A · D = shown as B · B = shown as C · E = shown as D · A = shown as E

The adult-onset, objectively confirmed asthma; exposure to a recognised workplace sensitiser; and reproducible improvement during sufficiently long periods away from work make occupational asthma likely. However, the health and employment consequences mean that occupational causation must not be diagnosed from history alone. He should be referred promptly to an occupational asthma specialist while he remains exposed. Serial peak expiratory flow is the usual first-line physiological assessment. A technically adequate record requires at least four readings daily for at least 3 weeks, including repeated periods at and away from work. Work times, tasks, exposures and medication use should be recorded, with maintenance treatment kept stable where possible. A is a potential specialist alternative when adequate serial peak-flow records cannot be obtained, but paired airway-responsiveness testing is not the preferred initial plan here. B removes the work–rest contrast and diagnostic tests lose sensitivity after exposure ceases. D is premature: specific inhalation challenge is resource-intensive, available only in specialist centres and generally reserved for cases unresolved by less invasive testing. E is incorrect because specific IgE may support sensitisation, but limited sensitivity—particularly for low-molecular-weight agents such as diisocyanates—means a negative result does not exclude occupational asthma; a positive result would not by itself demonstrate work-related bronchoconstriction.

Reference: British Thoracic Society Clinical Statement on occupational asthma (March 2022) — https://www.brit-thoracic.org.uk/document-library/clinical-statements/occupational-asthma/bts-clinical-statement-on-occupational-asthma/ Asthma: diagnosis, monitoring and chronic asthma management (BTS, NICE, SIGN) — Recommendations (27 November 2024) — https://www.nice.org.uk/guidance/ng245/chapter/recommendations