The BOREAS and NOTUS trials established that dupilumab reduces exacerbations in COPD with type 2 inflammation. This pooled analysis asks the question that matters more operationally: does that translate into fewer patients turning up at hospital, and less cumulative corticosteroid. It covers 1,874 patients aged 40 to 85 with moderate to severe airflow limitation and screening blood eosinophils of at least 300 cells per microlitre, randomised to dupilumab 300 mg or placebo for 52 weeks.
Emergency department visits and hospital admissions of any duration fell by 38% (rate ratio 0.62, 95% CI 0.43 to 0.90, p=0.0121). Time to first such event was delayed, and the risk of a first event fell by 45% (hazard ratio 0.55, 95% CI 0.38 to 0.78, p=0.0010). Systemic corticosteroid use fell by 42% among patients experiencing severe exacerbations (rate ratio 0.58, 0.38 to 0.89) and by 28% among those with moderate exacerbations (0.72, 0.60 to 0.87).
The corticosteroid finding deserves more attention than it usually gets. Cumulative oral steroid exposure in COPD is a slow, quiet source of harm — osteoporosis, diabetes, cataract, adrenal suppression, skin fragility — that accrues over years of exacerbations and is rarely counted when weighing a biologic. A 42% reduction in steroid courses among the patients who exacerbate severely is a genuine long-term benefit that sits outside the exacerbation count itself.
So when the eosinophil threshold is met, this is a stronger case than exacerbation rate alone suggests: fewer hospital attendances, delayed time to the first, and materially less steroid. The threshold is the constraint. These patients were selected at 300 cells per microlitre or above, so this evidence does not transfer to the larger group with lower eosinophils — for whom the astegolimab data above are the relevant development. In Indian practice, where an eosinophil count is cheap and universally available while the biologic is neither, the practical step is to make sure the count is actually being measured and recorded, so that the conversation can be had at all when access improves.
- In COPD with eosinophils at or above 300 cells per microlitre, dupilumab cut emergency attendances and admissions by 38%.
- Count the steroid benefit too: 42% fewer systemic corticosteroid courses among those with severe exacerbations.
- Record a blood eosinophil count in every COPD patient with frequent exacerbations; it determines eligibility.
- Do not extrapolate below the 300 cells per microlitre threshold used for enrolment.
- Cumulative corticosteroid harm is usually uncounted when weighing biologic cost — count it.
The statistics, in plain English
Two different measures appear here and they answer different questions. The rate ratio of 0.62 counts all events, so it reflects total burden across a year including repeat attendances. The hazard ratio of 0.55 concerns only the first event and how long patients went before it. They agree, which is reassuring. The intervals are wide — 0.43 to 0.90 for the rate ratio — because emergency attendances are relatively uncommon events even in this population, so the analysis rests on fewer events than the exacerbation counts do. This is a pooled analysis of prespecified endpoints from two completed trials, not a post hoc trawl, which strengthens it.
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