Reliability, Validity, and Responsiveness of the DEG, a Three-Item Dyspnea Measure

Abstract

Background: Dyspnea is a common and debilitating symptom that affects many different patient populations. Dyspnea measures should assess multiple domains.

Objective: To evaluate the reliability, validity, and responsiveness of an ultra-brief, multi-dimensional dyspnea measure.

Design: We adapted the DEG from the PEG, a valid 3-item pain measure, to assess average dyspnea intensity (D), interference with enjoyment of life (E), and dyspnea burden with general activity (G).

Participants: We used data from a multi-site randomized clinical trial among outpatients with heart failure.

Main measures: We evaluated reliability (Cronbach's alpha), concurrent validity with the Memorial-Symptom-Assessment-Scale (MSAS) shortness-of-breath distress-orbothersome item and 7-item Generalized-Anxiety-Disorder (GAD-7) scale, knowngroups validity with New-York-Heart-Association-Functional-Classification (NYHA) 1-2 or 3-4 and presence or absence of comorbid chronic obstructive pulmonary disease (COPD), responsiveness with the MSAS item as an anchor, and calculated a minimal clinically important difference (MCID) using distribution methods.

Key results: Among 312 participants, the DEG was reliable (Cronbach's alpha 0.92). The mean (standard deviation) DEG score was 5.26 (2.36) (range 0-10) points. DEG scores correlated strongly with the MSAS shortness of breath distress-or-bothersome item (r=0.66) and moderately with GAD-7 categories (ρ=0.36). DEG scores were statistically significantly lower among patients with NYHA 1-2 compared to 3-4 [mean difference (standard error): 1.22 (0.27) points, p<0.01], and those without compared to with comorbid COPD [0.87 (0.27) points, p<0.01]. The DEG was highly sensitive to change, with MCID of 0.59-1.34 points, or 11-25% change.

Conclusions: The novel, ultra-brief DEG measure is reliable, valid, and highly responsive. Future studies should evaluate the DEG's sensitivity to interventions, use anchor-based methods to triangulate MCID estimates, and determine its prognostic usefulness among patients with chronic cardiopulmonary and other diseases.

Keywords: Patient-reported outcome measure; cardiopulmonary disease; chronic obstructive pulmonary disease; dyspnea; heart failure; psychometrics.

Figure 1

Dyspnea, enjoyment of life, general activity (DEG) measure.

Figure 2

Distribution of DEG scores. DEG = dyspnea, enjoyment of life, general activity measure.

Figure 3

Concurrent validity of the DEG. A With the MSAS shortness-of-breath distress-or-bothersome item (r = 0.66, p < 0.01); B with GAD-7 anxiety levels (ρ = 0.36, p < 0.01). DEG = dyspnea, enjoyment of life, general activity measure; GAD-7 = 7-item Generalized Anxiety Disorder Scale; MSAS = Memorial Symptom Assessment Scale.

Figure 4

Known-group validity of the DEG. A By NYHA classification [mean difference (standard error) = 1.22 (0.27) points, p < 0.01]; B by presence or absence of COPD [mean difference (standard error) = 0.87 (0.27) points, p < 0.01]. COPD = chronic obstructive pulmonary disease; DEG = Dyspnea, Enjoyment of life, General activity measure; NYHA = New York Heart Association.