Breath-holding test in subjects with near-fatal asthma. A new index for dyspnea perception

Summary Rationale Identification of asthmatic subjects with low perception of dyspnea (POD) that are at higher risk of hospitalization, near-fatal and fatal asthma could improve their management. Objective Create a simple procedure that facilitate the recognition of low POD. Methods We enrolled near fatal asthma (NFA) subjects and a wide spectrum of non-NFA subjects. Each subject was asked to stop breathing at end-expiration. Dyspnea was assesssed by a modified Borg scale. To design the new index, we combined the Borg score at the end of the voluntary breath-holding maneuver with the airway limitation. The equation was as follows: FEV 1 /FVC%/(breath-holding time in seconds/final Borg score minus basal Borg score). Results Eleven NFA subjects (4 females) aged 21–73 yr and 55 non-NFA (14 severe, 18 moderate and 23 mild asthmatic subjects) completed the study. The threshold value of the index that could predict POD is sd ) of the new index perception was significantly lower in NFA group ( n =11; 5.21±3.59; vs. n =55; 13.67±11.08; P =0.006). This threshold value had 100% sensitivity and it best discriminated between mild and NFA groups. The negative likelihood ratio (when the index ⩾12) was zero. A result ⩾12 represented an almost null probability of poor POD. Conclusion The breath-holding test is simple and rapid. Its negative likelihood ratio was zero. Accordingly, a test result of 12 or greater might exclude the probability of poor perception of dyspnea in subjects with stable asthma.