Perception of breathlessness by a 3-minute respiratory exerciser test predicts asthma exacerbations: a prospective cohort study

We prospectively evaluated the use of a simple 3-Minute Respiratory Exerciser Test (3MRET) that estimates perception of dyspnea to identify patients at risk of asthma exacerbations. A total of 146 stable asthmatics (42 under-perceivers, 69 normal perceivers, and 35 over-perceivers) received follow-up for 12 months. The mean (SD) unscheduled visits to doctors among under-, normal, and over-perceivers were 1.8 (1.2), 2.2 (1.8), and 3.1 (2.3), respectively (p = 0.008). The mean (SD) hospital admissions among the groups were 1.3 (0.5), 1.2 (0.6), and 1.7 (1.3), respectively (p = 0.026). Compared to normal perceivers, over-perceivers had increased risks of unscheduled visits (OD: 5.12; 95% CI = 1.59 to 16.47) and hospital admissions (OD: 0.31; 95% CI = 0.23 to 0.41), defined as > or =2 events in 12 months. The association between over-perceiver and unscheduled visits remained significant after adjusting for forced expiratory volume in 1 second (FEV(1)). Sensitivity and specificity of over-perceivers are 77% and 47%, respectively, for unscheduled visits and 37% and 78%, respectively, for hospital admissions, with significantly better area under ROC for unscheduled visits (0.67 [95% CI = 0.56 to 0.77]; p = 0.003) than for hospital admissions (0.58 [0.471 to 0.70]; p = 0.127). We conclude that the 3MRET may have a role in identifying asthmatic patients with over-perception of dyspnea at risk of clinically important asthma exacerbations.