# Describing the burden of moderate exacerbations in patients with asthma from the Extended Salford Lung Study (Ext-SLS): a retrospective cohort study

## TL;DR

This study shows that frequent moderate asthma flare-ups are common and linked to worse health and higher costs, even in patients using standard asthma medications.

## Contribution

The study provides real-world evidence on the impact of moderate asthma exacerbations in patients on ICS/LABA therapy.

## Key findings

- 86.6% of patients in the study self-reported moderate asthma exacerbations in the 12 months prior to the index date.
- Patients with more frequent exacerbations had significantly worse asthma control and higher healthcare costs.
- Exacerbation frequency was associated with increased healthcare resource utilization and direct costs.

## Abstract

There is a need for real-world data describing the frequency and impact of moderate asthma exacerbations in patients receiving inhaled corticosteroids/long-acting β2-agonists (ICS/LABA). The Salford Lung Study (SLS) and associated extension study (Ext-SLS) evaluated ICS/LABA versus existing maintenance therapy in adults with asthma. This analysis assessed the impact of moderate exacerbations in patients from the Ext-SLS.

This retrospective cohort study analysed linked primary and secondary care and patient questionnaire data from patients enrolled in the Ext-SLS (indexed April 2018–May 2019). Primary outcome was number of self-reported moderate asthma exacerbations 12 months pre-index, overall, by maintenance treatment class and asthma control status at index, using the Asthma Control Test (ACT; poor [< 16], somewhat controlled [16–18], and controlled [> 19]) and 6-item Asthma Control Questionnaire (ACQ-6; uncontrolled [≥ 1.50], partially controlled [> 0.75–<1.50], and controlled [≤ 0.75]). Secondary outcomes included index ACT and ACQ-6 score, healthcare resource utilisation (HCRU) and direct costs 12 months pre- and post-index, stratified by self-reported moderate exacerbation frequency pre-index.

Of 485 patients with ≥ 12 months’ pre-index data, 86.6% (n = 420) self-reported moderate exacerbations, with similar frequency irrespective of maintenance treatment class (66.7–100.0%; ICS/LABA: 85.4%). Numerically greater proportions of patients self-reported a moderate exacerbation in the 12 months pre-index in ACT poor-control (n = 110/115 [95.7%]) and ACQ-6-uncontrolled (n = 200/210 [95.3%]) versus ACT- and ACQ-6-controlled (n = 205/260 [78.8%], n = 105/145 [72.4%]) groups. Symptom control worsened with increasing exacerbation frequency: mean (SD) ACT scores were 21.8 (3.3) and 15.7 (4.4) for patients with 0 or ≥ 7 events, respectively; mean (SD) ACQ-6 scores followed the same trend. Direct costs and HCRU increased with pre-index exacerbation frequency; mean (SD) all-cause and asthma-related total costs were £1509 (£2384) and £717 (£1459) for patients with no moderate exacerbations 12 months pre-index and £2002 (£2058) and £1086 (£1538) for patients with ≥ 7 exacerbations; similar trends occurred over 12 months post-index.

Patients with asthma experience frequent moderate exacerbations, which are associated with poor asthma control, increased HCRU and costs, emphasising the poor quality of life patients experience. Tackling poor adherence, risk behaviour, and comorbidities as well as holistic management and medication review are needed.

Registered on clinicaltrials.gov: NCT03152669, 12 May 2017

The online version contains supplementary material available at 10.1186/s12931-025-03199-5.