Severe Asthma Step-Up Therapy
A 38-year-old woman with asthma remains symptomatic on a medium-dose budesonide-formoterol inhaler twice daily, with daytime wheeze four days a week, night waking twice weekly, and salbutamol use four times a week. Inhaler technique is correct, adherence is confirmed, she has no rhinosinusitis or reflux, and she does not smoke. Spirometry shows an FEV1 of 68 percent predicted, and blood eosinophils are 0.18 × 10⁹/L. Which addition is most appropriate?
- A.Oral montelukast at bedtime
- B.Oral prednisolone 10 mg daily long term
- C.Inhaled tiotropium once dailyCorrect
- D.Increase salbutamol to regular four-hourly dosing
Explanation
When asthma remains uncontrolled on medium-dose inhaled corticosteroid combined with a long-acting beta-2 agonist, and adherence, inhaler technique, and comorbidities have been verified, the guideline-recommended step-up is to add a long-acting muscarinic antagonist such as tiotropium. Tiotropium blocks M3 receptor mediated bronchoconstriction and mucus secretion through a pathway independent of beta-2 stimulation, so it adds bronchodilation and reduces exacerbations without further increasing corticosteroid exposure. Trials show improved trough FEV1 and prolonged time to first severe exacerbation when tiotropium is added to inhaled corticosteroid plus long-acting beta-2 agonist. The alternative at this step is to increase to high-dose inhaled corticosteroid-long-acting beta-2 agonist, though gains flatten while systemic effects such as dysphonia, candidiasis, adrenal suppression, and bone loss accumulate. Biologic therapy is considered for severe uncontrolled disease with a defined phenotype, but this patient's eosinophil count of 0.18 × 10⁹/L does not meet the threshold for anti-interleukin-5 agents, and there is no evidence of allergic or type 2 high disease here. Maintenance oral corticosteroid is the last resort in severe refractory asthma because of adrenal suppression, osteoporosis, hyperglycaemia, cataracts, and weight gain, and it should never be reached before inhaled options are exhausted. Montelukast provides only modest benefit in most adults and carries a boxed warning for neuropsychiatric adverse effects, so it ranks below a long-acting muscarinic antagonist. Scheduled short-acting beta-2 agonist dosing does not improve control, promotes tolerance, and is associated with worse outcomes, so relievers should be used only as needed.
Why each option
- A.
- Montelukast gives modest additional benefit and carries neuropsychiatric warnings, making it inferior to a long-acting muscarinic antagonist at this step.
- B.
- Continuous oral corticosteroid is reserved for severe refractory disease after all inhaled and biologic options have failed.
- C.
- Correct. Adding a long-acting muscarinic antagonist is the recommended step-up when symptoms persist on inhaled corticosteroid plus long-acting beta-2 agonist.
- D.
- Scheduled short-acting beta-2 agonist use causes receptor tolerance and worse outcomes; relievers should be used only when needed.
Reference: GINA 2024 Global Strategy for Asthma Management and Prevention
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