The study used de-identified records from New Zealand’s National Minimum Dataset and Pharmaceutical Collection, linking national hospital diagnoses with subsidised medicines dispensed through community and outpatient pharmacies. The investigators classified patients into nine mutually exclusive medication regimens using the inhaler classes dispensed during the three months ending with each patient’s final asthma-inhaler dispensing date in two two-year periods: 1 July 2018 to 26 June 2020 and 27 June 2020 to 30 June 2022. The primary cohort included patients aged at least 12, while children younger than 12 formed a comparison group. This design allowed medication changes to be tracked within individuals rather than inferred from aggregate prescribing totals, although the authors cautioned that dispensing records do not reveal whether patients actually used the medicines they received.

The most important change involved patients already receiving maintenance treatment together with a separate reliever. Among people dispensed ICS with SABA before the guideline update, 17.9% subsequently received ICS-formoterol without SABA, while 6.4% moved to ICS-formoterol with SABA still co-dispensed. Among those using non-formoterol ICS–long-acting β2-agonist therapy with SABA, 10.4% switched to ICS-formoterol without SABA and 5.8% to ICS-formoterol with SABA. The study’s difference-in-differences analysis placed the guideline-attributable reduction in concurrent SABA use among maintenance regimens at 5.7 percentage points for ICS with SABA and 3.2 percentage points for non-formoterol ICS–LABA with SABA. By contrast, SABA monotherapy declined by 7.2 percentage points in the eligible cohort and 7.0 points in the younger comparison group, producing a negligible difference-in-differences estimate of −0.2 percentage points.

That distinction matters because the apparent reduction in SABA supply did not primarily represent a large-scale conversion of SABA-only patients to anti-inflammatory reliever therapy. Of 99,224 patients dispensed SABA alone at baseline, 57.1% remained in that category after the update. Another 17.6% moved to ICS-formoterol without SABA and 8.1% to ICS-formoterol with SABA. Overall, 55.7% of the primary cohort remained on its existing therapy. The study therefore suggests that the guideline chiefly redirected patients who were already engaged in maintenance care, while the much larger SABA-only group changed more slowly. This is an important distinction between dispensing patterns and clinical outcomes: the research did not measure exacerbations, symptom control, hospital admissions after the intervention, or other clinical endpoints, so it cannot establish that the prescribing shift reduced asthma-related morbidity.

Concurrent SABA supply remained common among people using ICS-formoterol. During the post-guideline period, 31.1% of ICS-formoterol users were also dispensed a SABA within the same three-month window, compared with 63.8% of those using non-formoterol ICS–LABA and 70.2% of those using ICS. Co-dispensing declined among ICS-formoterol users from 42.1% before the guideline change to 31.1% afterward. Of patients who had received ICS-formoterol with SABA before the update, 32.5% no longer had SABA dispensed in the later period, whereas 54.1% continued to receive both medicines. The measure identifies overlapping supplies rather than simultaneous possession or use, meaning it is an upper bound on sustained dual therapy rather than a direct measure of daily inhaler use.

Uptake also varied by age. Among patients aged 12 to 44, overall ICS-formoterol use increased from 18.4% to 37.3%, an absolute rise of 18.9 percentage points, compared with an increase from 19.2% to 32.0% among those aged 45 or older. Of baseline SABA-only patients, 19.7% in the younger group moved to ICS-formoterol without SABA, versus 15.6% in the older group. Persistence on established maintenance therapy was greater among older patients: 78.7% of those aged at least 45 remained on non-formoterol ICS–LABA, compared with 68.5% of those aged 12 to 44. The persistence of the overall pattern in the younger age stratum, where COPD is less prevalent, argues against misclassified chronic obstructive pulmonary disease or asthma–COPD overlap fully explaining the observed shift, although the absence of diagnostic confirmation means it cannot be excluded.

The comparison with children supports a role for the recommendation itself. ICS-formoterol without SABA increased from 1.0% to 5.5% among children younger than 12, but only 3.6% of their baseline SABA-only users moved to that regimen, compared with 17.6% in adolescents and adults. The younger cohort experienced the same pandemic-related health-system environment and other national influences, but did not receive the same recommendation. The authors noted several limitations to this comparison: children differ in disease natural history, prescribers and device suitability, and parallel trends could not be verified with only two time points. The study also took place during the COVID-19 pandemic, when hospital use and patterns of primary-care access changed. Other influences included successive annual GINA updates, a New Zealand trial that may have affected practice before publication of the national guideline, and PHARMAC’s later funding of a second budesonide-formoterol brand, which the data could not separate from the guideline effect.

Several features of the New Zealand implementation may have helped produce the observed prescribing change. The 2020 national guidelines aligned adolescent and adult care with the GINA strategy, and PHARMAC funded an additional budesonide-formoterol dry-powder inhaler to increase competition and widen access. The study’s authors also cited multidisciplinary development of guidelines across health professions, a primary-care quick-reference guide, and rapid updating of prescribing education. Yet the findings do not establish that unrestricted funding alone caused the shift, nor do they show that every unchanged regimen represented poor adherence to the guideline. Some patients may have remained on traditional therapy because their asthma was well controlled, because a different device was more suitable, or because of individual clinical judgement. The study measured dispensing, not prescribing intent or patient experience.

The cohort is also smaller than New Zealand’s commonly reported asthma prevalence of roughly 600,000 people, because the analysis required evidence of active disease and excluded patients with no recorded diagnosis or asthma-inhaler dispensing during follow-up. The authors said it is unclear whether people outside the cohort had achieved remission, were using stockpiled inhalers, had stopped treatment, or were experiencing gaps in care. Linked administrative data cannot confirm diagnoses, medication-taking, inhaler possession, or clinical outcomes, and they do not distinguish ICS-formoterol used as an anti-inflammatory reliever from maintenance and reliever therapy. The findings therefore describe a substantial real-world change in dispensing, especially among maintenance-treated adolescents and adults, while leaving the long-term clinical consequences and the large SABA-only population for further study.

Subject of Research: Real-world implementation of anti-inflammatory reliever therapy for asthma in New Zealand

Article Title: Implementation of the National Asthma Guidelines in New Zealand: a retrospective patient-level study of the change to anti-inflammatory reliever therapy in 324,972 patients

Article References: Cheng, F. W. T., Gong, J., Tomlin, A., Harrison, W., Beyene, K., Reddel, H. K., Harrison, J., Hew, M., & Chan, A. H. Y. (2026). Implementation of the National Asthma Guidelines in New Zealand: a retrospective patient-level study of the change to anti-inflammatory reliever therapy in 324,972 patients. The Lancet Regional Health – Western Pacific, 75, Article 102002. https://doi.org/10.1016/j.lanwpc.2026.102002

Image Credits: AI Generated

DOI: 10.1016/j.lanwpc.2026.102002

Keywords: asthma, anti-inflammatory reliever therapy, ICS-formoterol, SABA, New Zealand, guideline implementation, health policy, pharmacoepidemiology, medication dispensing, Implementation, National, Guidelines