Additional evidence for the affective dimension of dyspnea in patients with COPD

Abstract

The primary purpose of this secondary analysis was to determine whether 103 participants with chronic obstructive pulmonary disease rated the affective dimension of dyspnea (dyspnea-related anxiety and dyspnea-related distress) separately from the sensory dimension (intensity) during baseline exercise testing conducted as part of a randomized clinical trial. A secondary purpose was to determine if dyspnea-related anxiety and distress were rated distinctly different from other measurements of anxiety. At the end of a 6-minute walk and an incremental treadmill test, participant ratings of the magnitude of dyspnea-related anxiety and distress on the Modified Borg Scale were significantly different from their ratings of the intensity of dyspnea. Dyspnea-related anxiety and distress also appeared to be concepts independent from measures of state anxiety, negative affect, and anxiety before a treadmill test.

FIGURE 1

Modified Borg scores (Mean _ SD) for the magnitude of the measures of the sensory and affective dimensions of dyspnea before and after the 6-minute walk. Note: Before the 6-minute walk (6MW) at rest, the difference between the magnitude of dyspnea intensity (SOB) and dyspnea-related distress (DD) was .35 (p < .001), the difference between the magnitude of SOB and dyspnea-related anxiety (DA) was .345 (p < .005), and the difference between the magnitude of DD and DA was not significant. At the end of the 6MW, the difference between the magnitude of SOB and DD was 1.67 (p < .0001), the difference between the magnitude of SOB and DA was 2.12 (p < .0001), and the difference between the magnitude of DD and DA was .434 (p < .001).

FIGURE 2

Modified Borg scores for the magnitude of intensity and affective dimensions of dyspnea during incremental treadmill exercise. Note: At rest prior to the Incremental Treadmill Test (ITT), the differences between the magnitude of dyspnea intensity (SOB), dyspnea-related distress (DD), and dyspnea-related anxiety (DA) were not significant. At ITT Isostage, defined as the highest stage completed during two ITTs, the difference between the magnitude of SOB and DD was 1.08 (p < .001), the difference between the magnitude of SOB and DA was 1.24 (p < .0001), and the difference between the magnitude of DD and DA was .193 (p < .05). At the end of the ITT, the difference between the magnitude of SOB and DD was 1.25 (p < .001), the difference between the magnitude of SOB and DA was 1.45 (p < .001) and the difference between the magnitude of DD and DA was .201 (p < .0001).

FIGURE 3

Mean slopes of modified Borg scores of intensity and affective dimensions of dyspnea related to minute ventilation (VE) during incremental treadmill exercise. Note: The mean slope of dyspnea intensity (SOB) related to minute ventilation (VE) over time during incremental treadmill test (ITT) was .23 (SD ¼.18). The mean slope of dyspnea-related distress (DD) related to VE over time during ITT was .20 (SD ¼.27). The mean slope of dyspnea-related anxiety (DA) related to VE over time during ITT was .18 (SD ¼.25). The difference between the mean slope of SOB related to VE (SOB/VE) and the mean slope of DD related to VE (DD/VE) was .028 (p < .001). The difference between SOB/VE and the mean slope of DA related to VE (DA/VE) was .046 (p < .001). The difference between DD/VE and DA/VE was .017, p ¼.05.