Objective: The majority of studies show that treatment adherence in chronic diseases such as asthma does not exceed 50%. Although the reasons may vary, it is clear that lack of treatment adherence is a determining factor in poor disease control. An association has also been observed between lack of perception of dyspnea and difficult-to-control asthma and with the occurrence of fatal or near-fatal asthma attacks. In this study we therefore attempted to demonstrate that one of the reasons that asthmatic patients do not adhere to treatment is a failure to perceive dyspnea associated with bronchial obstruction.
Patients and methods: We analyzed 2 groups of patients with moderate persistent asthma who had all been prescribed the same chronic treatment (a dose of inhaled drug administered with a dry powder inhaler every 12 hours). The first group comprised 24 patients (16 women and 8 men; mean [SD] age, 44 [15] years) who took the medication almost every day. The second group contained 24 patients (16 women and 8 men; mean [SD] age, 48 [14] years) who did not use the medication or only took it occasionally. There were no significant differences between the groups in terms of age, sex, percentage of smokers, socioeconomic and educational level, anxiety, depression, or spirometry variables. A histamine challenge test was carried out in all patients and the dyspnea perceived after each dose of the drug was measured on a modified Borg scale. The dose of histamine leading to a 20% reduction in forced expiratory volume in 1 second (FEV(1)), perception of dyspnea associated with a 20% reduction in FEV(1) (PS(20)), and the change in dyspnea measured on the Borg scale between baseline and 20% reduction in FEV(1) were analyzed. Patients were also classified as poor perceivers of dyspnea if the change in perception of dyspnea on the modified Borg scale was less than or equal to zero.
Results: The group of patients with poor treatment compliance had a lower PS(20) (2.27 [1.9] vs 3.51 [1.8], P=.03) and change in Borg score (1.64 [1.9] vs 2.7 [1.84], P=.057), and they were more often poor perceivers of dyspnea (50% vs 21%, P=.034).
Conclusions: There is a relationship between treatment adherence and dyspnea perception, such that poor perception is among the reasons for poor treatment adherence in patients with asthma.