Asthma Clinical Research Network (ACRN) IMProving Asthma Control Trial (IMPACT)

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Accession Number

Study Type
Clinical Trial

Collection Type
Open BioLINCC Study See bottom of this webpage for request information

Study Period
May 2000 - May 2003

NHLBI Division

Dataset(s) Last Updated
July 17, 2020


Commercial Use Data Restrictions No

Data Restrictions Based On Area Of Research No


Although guidelines recommend daily therapy for patients with mild persistent asthma, prescription patterns suggest that most such patients use these so-called controller therapies intermittently. In patients with mild persistent asthma, we evaluated the efficacy of intermittent short-course corticosteroid treatment guided by a symptom-based action plan alone or in addition to daily treatment with either inhaled budesonide or oral zafirlukast over a one-year period.


Treatment guidelines recommend daily antiinflammatory therapy to control mild persistent asthma. This recommendation for so-called controller therapy was prompted by studies reporting that such treatment improves physiological measures of airway obstruction (peak expiratory flow [PEF] and forced expiratory volume in one second [FEV1]), the severity of symptoms, the frequency of exacerbations, and the quality of life and was reinforced by reports that inhaled corticosteroid treatment may prevent progressive loss of pulmonary function. However, analysis of pharmacy records suggests that most patients infrequently renew their prescriptions for controller medications (inhaled corticosteroids and leukotriene-receptor antagonists). We reasoned that patients with mild asthma may be using their treatment intermittently because they do not perceive the need for daily therapy. To analyze whether this strategy could be an acceptable approach to treatment in patients with mild persistent asthma, we modified a symptom-based action plan to guide the use of inhaled or oral corticosteroids when signs or symptoms of asthma worsened.


Inclusion criteria were physician-diagnosed asthma, an age of 18 to 65 years, and an FEV1, measured more than four hours after the most recent use of a bronchodilator, that was at least 70 percent of the predicted value. All patients had an increase in the FEV1 of at least 12 percent and at least 200 ml after the inhalation of albuterol or a fall in FEV1 of at least 20 percent after inhaling a concentration of methacholine of less than 16 mg per milliliter (PC20; lower concentrations indicate greater reactivity).


In a double-blind trial, 225 adults underwent randomization. Patients were assigned to one of three parallel treatment groups: twice-daily oral placebo and inhalation of 200 µg of budesonide, twice-daily oral zafirlukast (20 mg) and inhalation of placebo, or twice-daily oral and inhaled placebo (intermittent treatment). The primary outcome was morning peak expiratory flow (PEF). Other outcomes included the forced expiratory volume in one second (FEV1) before and after bronchodilator treatment, the frequency of exacerbations, the degree of asthma control, the number of symptom-free days, and the quality of life.


The three treatments produced similar increases in morning PEF (7.1 to 8.3 percent; approximately 32 liters per minute; P=0.90) and similar rates of asthma exacerbations (P=0.24), even though the intermittent-treatment group took budesonide, on average, for only 0.5 week of the year. As compared with intermittent therapy or daily zafirlukast therapy, daily budesonide therapy produced greater improvements in pre-bronchodilator FEV1 (P=0.005), bronchial reactivity (P<0.001), the percentage of eosinophils in sputum (P=0.007), exhaled nitric oxide levels (P=0.006), scores for asthma control (P<0.001), and the number of symptom-free days (P=0.03), but not in post-bronchodilator FEV1 (P=0.29) or in the quality of life (P=0.18). Daily zafirlukast therapy did not differ significantly from intermittent treatment in any outcome measured.

It may be possible to treat mild persistent asthma with short, intermittent courses of inhaled or oral corticosteroids taken when symptoms worsen. Further studies are required to determine whether this novel approach to treatment should be recommended.

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