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.
Perceived breathlessness played an important role in guiding treatment in asthma. We developed a simple, user-friendly method of scoring perception of dyspnoea (POD) using an incentive spirometer, Triflo II (Tyco Healthcare, Mansfield, USA) by means of repetitive inspiratory efforts achieved within three minutes in 175 normal healthy subjects and 158 asthmatic patients of mild (n=26), moderate (n=78) and severe (n=54). Severity was stratified according to GINA guideline. The mean POD index in normal subjects, and asthmatic patients of mild, moderate and severe severity were: 6 (4-7) 16 (9-23), 25 (14-37), and 57 (14-100) respectively (p<0.001 One-Way ANOVA). Based on 17 asthmatic and 20 normal healthy subjects, intraclass correlation coefficients for POD index within subjects were high. In 14 asthmatic patients randomized to receiving nebulised b(2)-agonist or saline in a crossover, double-blind study, % FEV(1) change correlated with % changes in POD index [r(s) -0.46, p=0.012]. Finally, when compared with 6-minutes walking test (6MWT) in an open label study, respiratory POD index correlated with walking POD index in 21 asthmatic patients [r(s)= 0.58 (0.17 to 0.81) (p=0.007] and 26 normal subjects [0.50 (0.13 to 0.75) (p=0.008)]. We concluded that this test is discriminative between asthmatic patients of varying severity and from normal subjects, is reproducible, responsive to bronchodilator effect, and comparable with 6MWT. Taken together, it has the potential to score disability and POD in asthma effectively and simply.