Introduction

Short-acting beta-agonists (SABA) have long been regarded as essential as a reliever medication to treat acute symptoms of asthma and to prevent symptoms in response to known triggers (e.g., exercise or allergen exposure). However, overuse of SABA is a powerful indicator of poor asthma control. Patients and some healthcare professionals frequently believe that asthma symptoms and the need for frequent SABA use are simply a fact of life in living with asthma (Box 1).

Patients are given SABA early in the course of asthma management, often even before undergoing lung function testing. As-needed (PRN) SABA was recommended as the first step of management in older asthma treatment guidelines [1]. Thus, from the very beginning of their asthma management, patients came to believe that treating symptoms alone was acceptable [2]. In addition, the effects of SABA are felt immediately, giving patients the perception that it is helping control their asthma. As a result, SABA becomes viewed by patients as a “quick fix” compared with no immediate perceptible relief from inhaled corticosteroid (ICS) control [3]. When patients believe that their symptoms are being controlled by frequent SABA use, they negate the importance of concomitant ICS-containing controller use, leading to intentional or non-intentional non-adherence to controller ICS or denial of the need for it [2, 4]. Such situations can be dangerous since studies have demonstrated a clear relationship between high-dose or frequent (i.e., ≥ 3 canisters per year) SABA use and a deterioration of asthma control, risk of exacerbations, and mortality. [5,6,7]

The Global Initiative for Asthma has evolved its treatment paradigm so that low dose ICS/formoterol is now the preferred reliever approach for adults and adolescents, even at the mildest asthma severity [8]. PRN SABA is reserved for those who are on a controller medication, without exacerbations, and for whom ICS/formoterol is not possible or not preferred [8]. In their 2021 update on the diagnosis and management of very mild to mild asthma, the Canadian Thoracic Society (CTS) recommended that a combination ICS and long-acting beta-agonist (LABA), specifically budesonide/formoterol, may be used PRN as an alternative reliever to SABA [9]. The use of a PRN ICS plus a fast-acting LABA is a win–win situation, providing quick relief (within 5 min) that the patient can sense, while administering at least some degree of controller ICS medication. PRN budesonide/formoterol is approved as a reliever medication for ages ≥ 12 years in Canada. An algorithm was developed by the CTS as a guide for deciding for whom PRN budesonide/formoterol versus PRN SABA as monotherapy in very mild asthma would be appropriate as a reliever [9]. The algorithm suggests that adults and adolescents who are well controlled on PRN SABA or on no medication (e.g., very mild asthma) who are not at higher risk of exacerbations can continue on PRN SABA. “Higher risk” for exacerbations is defined as having any of the following: any history of a previous severe asthma exacerbation requiring systemic steroids, an emergency department visit, or hospitalization; poorly controlled asthma per CTS criteria; use of more than 2 SABA inhalers a year, or current smoker (Fig. 1). The definition of “well controlled” by CTS criteria is detailed and has some caveats (Fig. 1) [9]. While the CTS algorithm provides necessary and precise guidance, the somewhat complicated requirements for determining control and exacerbation risk may still end up leaving some patients at-risk to over rely on SABA if the patient overestimates their asthma control or simply ignores worsening symptoms. Furthermore, patients may not understand that more severe asthma may appear as episodic when in actuality it is not. Therefore, the goal of this communication is to simplify the reliever decision algorithm developed by the CTS for application in daily practice.

Fig. 1
figure 1

Reliever selection for patients with very mild or mild asthma. Higher exacerbation risk and poorly controlled asthma as defined by the Canadian Thoracic Society [9]. As-needed (PRN) short-acting beta-agonist (SABA) should be reserved only for patients with very mild or mild asthma who are not over-reliant on SABA, whose asthma is well-controlled on SABA alone, and who are not at higher risk for exacerbation. ED, emergency department; FEV1 forced expiratory volume in 1 s, ICS inhaled corticosteroid, PEF peak expiratory flow

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Simplified evaluation of SABA overreliance

Two SABA puffs twice-weekly equates to 208 doses per year, and each SABA canister has 200 doses. A 30-s evaluation of 2 simple questions can usually accurately assess if a patient’s asthma is controlled:

  1. 1.

    How many SABA canisters do you use a year?

  2. 2.

    How many times do you use SABA a week?

If the patient indicates use of > 2 SABA canisters per year or > 2 administrations of SABA per week, for any reason including prevention of exercise-induced asthma or in anticipation of allergen-induced symptoms, the patient does not have controlled asthma. Those individuals who have controlled asthma based on the responses to the 2 questions above and who are at low risk of exacerbations are the individuals for whom PRN SABA is still adequate, assuming they are adherent to their controller therapies when prescribed. On the other hand, those individuals whose responses indicate their asthma is uncontrolled should be prescribed, at minimum, a daily ICS with PRN SABA, or for those over 12 years PRN budesonide/formoterol could be an alternative, as a starting point. The CTS actually recommends ICS plus PRN SABA over PRN ICS/formoterol based on results from the SYGMA1 study, which demonstrated that ICS plus PRN SABA compared with PRN ICS/formoterol resulted in significantly more well-controlled asthma weeks (44.4% vs 34.4%, respectively) and a similar annualized severe exacerbation rate (0.09 vs 0.07, respectively) [9, 10]. The exception is if poor adherence is considered, in which case PRN ICS/formoterol is preferred [9]. Incorporating a corticosteroid-containing therapy at the beginning of asthma treatment could change patient relationships with their SABA. Encouraging regular ICS use or beginning with ICS are both options. Irrespective of the new regimen selected (daily ICS with PRN SABA or PRN ICS/formoterol), making this change to allow for protection against overreliance on SABA and achieve well controlled asthma can be life-changing for patients (Box 1). Having a patient complete the Reliever Reliance Test may provide a better understanding of why a patient is over-reliant on SABA (Fig. 2) and give the clinician an opportunity to meaningfully discuss the issue with the patient. [11]

Fig. 2
figure 2

Reproduced with permission from Prof. Rob Horne.

Reliever reliance test. [11]

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Two studies, one randomized double-blind [10] and one randomized open-label [12], have demonstrated a decrease in the rate of severe exacerbations when low dose ICS/formoterol is used as a reliever medication compared with PRN SABA alone. Thus, PRN budesonide/formoterol is a superior and safer option than PRN SABA for most adult and adolescent patients using excessive SABA therapy, who have very mild to mild asthma, and who are not on a daily controller medication. However, stepping up to PRN ICS/formoterol from PRN SABA may still not be sufficient to provide adequate control. Patients who are using PRN ICS/formoterol should also be asked how many times they use this form of medication a week as a reliever. More than 2 administrations per week should mandate a clinical review, with verification of the asthma diagnosis to rule out vocal cord disorder or obesity-related dyspnea and reevaluation of their asthma management strategy, including treatment augmentation to a regular controller therapy.

Conclusions

Excessive reliance on SABA therapy is potentially harmful for patients with asthma, adversely affecting their quality of life and increasing their risk of exacerbations and mortality. Using the reliever decision algorithm developed by the CTS or the simplified approach we propose, very few patients will actually fit into the PRN SABA-only category (Fig. 1). An education process is paramount to inform patients, caregivers, physicians, and healthcare providers, such as pharmacists, that overuse of any reliever is not acceptable therapy, is potentially harmful, and needs further evaluation and management.