MEETING HIGHLIGHT

Widespread SABA overuse and its implications on asthma control

31 Dec 2020
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Professor Eric Bateman

Pulmonology & Department of Medicine,
University of Cape Town & University of Cape Town Lung Institute,
South Africa

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Professor Jennifer Quint

Faculty of Medicine, National Heart and Lung Institute,
Imperial College,
London, United Kingdom

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Mr. Stephen Noorduyn

Medical Evidence Lead,
AstraZeneca,
Mississauga, Canada

For decades, the use of SABAs has been recommended both as initial treatment and for symptomatic relief in patients with varying severities of asthma. Recent studies have shown that treatment with inhaled corticosteroids (ICS) reduces the risk of exacerbations when compared to treatment with SABA alone.1–3 These studies, coupled with earlier safety concerns regarding SABA use, led to a significant update in the 2019 Global Initiative for Asthma (GINA) guidelines, which no longer recommend treatment with SABA alone, but instead recommend as-needed low-dose ICS-formoterol relievers for GINA steps 1 and 2, and ICS-formoterol maintenance and reliever therapy for steps 3-5.4 Despite this recent change in the treatment guidelines, the lack of data on SABA and ICS prescription trends has made it difficult to measure its effect. The SABINA global program was started in March 2019 to describe the extent of SABA use and its impact on asthma-related health outcomes.5 At the recent European Respiratory Society (ERS) International Congress 2020, Professor Jennifer Quint presented the main findings of SABINA, while Mr. Stephen Noorduyn described the SABINA results specific to Nova Scotia, Canada. Professor Eric Bateman followed by describing the patient characteristics associated with asthma symptom control.

Poor asthma control is common and results in substantial health and economic costs

Prof. Bateman shared that “poor asthma control is widespread and has improved only marginally over the last two decades.6” In the cross-sectional, self-reported European National Health and Wellness Surveys that were conducted in France, Germany, Italy, Spain, and the United Kingdom (UK), asthma control was assessed using the Asthma Control Test™, which was validated with GINA defined levels of asthma control.7 The overall proportion of treated asthma patients who were considered not having well-controlled asthma were 55.0% in 2006, 56.6% in 2008, and 53.5% in 2010.7 Additionally, a large cross-sectional study of American health plan members aged ≥6 years found that asthma-related healthcare costs increased with SABA utilization (3.0 times higher for excessive SABA users and 2.2 times higher for high SABA users, compared to low SABA users) over a 2 year period.8 SABA use was categorized counting canister equivalents per year as low (½ to 2), moderate (2½ to 6), high (6½ to 12), and excessive (more than 12).8 As the failure to maintain asthma symptom control and reduce exacerbation risk can lead to significant health and economic burden, the extent of SABA overuse and ICS underuse should be investigated.

Patterns of SABA overuse in Europe and US

In the retrospective observational study SABINA, SABA and ICS prescription/possession data from electronic medical records and/or national patient registries were obtained from the UK (SABINA I), the 4 countries: Canada, France, Spain, and the Netherlands (SABINA II), and the 2 countries: Poland and the United States (US) (SABINA+).9 Over one million subjects aged ≥12 years who used at least one SABA canister at baseline or the year of analysis, and had no other chronic respiratory conditions were enrolled. While most patients had mild asthma (60.7%), patients from Canada (Alberta, 58.6%), Poland (66.7%), the Netherlands (68.8%), and Spain (73.4%) had mostly moderateto- severe asthma.9 Overall, 39.9% of patients were prescribed or possessed ≥3 SABA canisters per year, ranging from 26% in the Netherlands to 63.2% in Nova Scotia, Canada.9

The association between SABA prescription/possession (≥3 vs. 1-2 canisters) and asthma exacerbations was assessed using a negative binomial model adjusted for age, sex, comorbidities, prior-year exacerbations, 2017 GINA steps, and maintenance therapy prescription/possession.9 Exacerbations were defined by oral corticosteroid prescriptions, emergency department visits, or asthma-related hospitalizations.9 Across all GINA steps and datasets with the exception of data from the US Medicare, prescription/possession of ≥3 versus 1-2 SABA canisters per year showed a statistically significant association with increased exacerbations (Figure 1).9 This association was independent of anti-inflammatory maintenance therapy prescription/possession. In addition, 35% of GINA patients at steps 2-5 were prescribed or possessed anti-inflammatory maintenance therapy ≥50% of the time (Figure 2).9 Asthma exacerbations persisted even among this group of patients with anti-inflammatory maintenance therapy.

Particularly in Nova Scotia, the use of >1-2 SABA canisters per year was associated with a 3% lower risk of outpatient asthma visits per year when compared to the reference category of ≤1 SABA canisters per year.10 The risk of outpatient asthma visits also increased with greater numbers of canisters used per year and was 73% higher among patients who used >12 canisters per year when compared to the reference category (Figure 3).10 Mr. Noorduyn concluded, “These results supported the GINA 2019 statement on the risks of SABA overreliance in patients leading to increased healthcare resource utilization as indicated by increased physician visits, emergency department visits and hospitalizations.”

 

Prof. Quint shared that the next steps of the SABINA program are to “assess prescription/possession of SABA as a continuous variable” and to “determine whether any prescription/possession of SABA without concomitant ICS is safe”. Additionally, further context around patient’s quality of life and patient’s adherence behaviors will provide important insights into how to better interpret the program findings and how to potentially decrease SABA use in the future.11

Factors associated with asthma symptom control

Following the SABINA study which revealed SABA overuse in over one-third of patients, the SABINA III cross-sectional study was initiated to understand factors associated with poor asthma control in both primary and specialty care settings in 24 countries on 5 continents.6 This study enrolled patients ≥12 years old with at least 3 consultations with a healthcare practitioner or practice.6 Ordinal regression models were used to identify determinants of asthma symptom control across asthma severities.6 Asthma symptom control and severity were assessed by the 2017 GINA criteria.

Specialist care (odds ratio (OR)=1.17, 95% CI: 1.04-1.32), university or post-university education (OR=1.17, 95% CI: 1.05-1.31), and no smoking history (OR=1.11, 95% CI: 1.00-1.24) were associated with better asthma control (Figure 4).6 Lack of reimbursed healthcare (OR=0.63, 95% CI: 0.57-0.69) and being overweight (OR=0.85, 95% CI: 0.77-0.95) or obese (OR=0.82, 95% CI: 0.73-0.91) were associated with poorer asthma control (Figure 4).6 Healthcare reimbursement and university education or above were significantly associated with symptom control in both mild and moderatesevere- asthma.6 No smoking history significantly increased the odds of symptom control for moderate-to-severe-asthma only.6 12

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