[Agreement in asthmatics' perception of dyspnea during acute and chronic obstruction]

Three types of asthmatic patients can be identified during periods of clinical stability: "poor perceivers," "normal perceivers," and "over perceivers." When asthmatics undergo bronchial challenge in the laboratory, the same distinctions in type of perception can be observed. The aim of the present study was to determine the level of agreement between the 2 situations.

A total of 93 patients with persistent moderate asthma (36 men and 57 women; mean age 40 years) were studied. We asked them to assess their dyspnea on a modified Borg scale when stable and after each histamine dose in a bronchial provocation test. When a patient's Borg scale assessment in stable situation was below the 25th percentile, that patient was classified as a poor perceiver. Patients were considered over perceivers if their score in stable situation was in the 75th percentile. Others were labeled normal perceivers. Type of perception during acute bronchoconstriction was defined in function of the change in Borg assessment once forced expiratory volume in the first second had decreased 20%: poor perceivers were those whose change in Borg assessment was in the 25th percentile, over perceivers were in the 75th percentile, and normal perceivers in the middle percentiles.

In stable situation, 23 patients were poor perceivers, 58 were normal perceivers, and 12 were over perceivers. During bronchoconstriction, there were 23 poor perceivers, 47 normal perceivers, and 23 over perceivers. Agreement was estimated by a kappa index of 0.0574 for poor perception, 0.1521 for over perception, and 0.3980 for normal perception.

Asthmatics' perception of dyspnea during periods of stability and during acute bronchoconstriction are independent phenomena. It is therefore not possible to infer how a patient will perceive an asthmatic attack by evaluating only how he or she perceives breathlessness during stable periods.