Variability of symptoms in mild persistent asthma: baseline data from the MIAMI study

To describe the variability of the asthma phenotype in patients with mild persistent asthma enrolled in the Mild Asthma Montelukast versus Inhaled Corticosteroid (MIAMI) study.

The variability of asthma rescue-free days, asthma symptoms, albuterol use, medical resource use, and exercise Limitations among patients with documented mild persistent asthma was compared between the month before study enrollment and the last 2 weeks of the run-in period.

Patients eligible for randomization (n = 400), aged 15-85 years, exhibited symptoms (mean +/- SD) 3.6 +/- 1.3 days/week, beta-agonist use 3.5 +/- 1.3 days/week, and normal FEV1 (94.0 +/- 9.9% predicted) during the last 2 weeks of the run-in period. In the year before enrollment, medical intervention for asthma flares was common: 38.5% made office visits, 15.8% had oral corticosteroids, and 8.3% required emergency room or hospitalized care. In the month before enrollment, 11.8% experienced daily symptoms, and 28.3% had limitations of normal activity. Patients with daily symptoms in the month before study enrollment, compared with those having less-than-daily symptoms, experienced fewer rescue-free days (P = 0.024) and had more days per week with symptoms (P = 0.008) and requiring albuterol (P = 0.048) during the run-in; FEV1 was similar for both groups (93.1% vs. 94.2% predicted, respectively).

Patients with mild persistent asthma reported a substantial disease burden in the year before enrollment. The asthma burden experienced by these patients both before and during the run-in period was of sufficient severity to support the recommendation that mild persistent asthma should be managed with daily controller therapy.