Activity-related dyspnea is not modified by psychological status in people with COPD, interstitial lung disease or obesity

Sensory (physiological) and affective (psychological) dimensions of dyspnea have been described but the usefulness of measuring psychological status in addition to ventilatory capacity (spirometry, lung volumes) in the assessment of exertional dyspnea remains controversial. We hypothesized that activity-related dyspnea would not be modified by psychological status. Principal component analysis (PCA) was used to reduce the number of parameters (psychological or functional) to fewer independent dimensions in 328 patients with altered ventilatory capacity: severe obesity (BMI ≥ 35, n = 122), COPD (n = 128) or interstitial lung disease (n = 78). PCA demonstrated that psychological status (Hospital Anxiety-Depression, Fatigue Impact scales) and dyspnea (Medical Research Council [MRC] scale) were independent dimensions. Ventilatory capacity was described by three main dimensions by PCA related to airways, volumes, and their combination (specific airway resistance, FEV1/FVC), which were weakly correlated with dyspnea. In conclusion, in patients with COPD, interstitial lung disease or severe obesity, psychological status does not modify activity-related dyspnea rating as evaluated by the MRC scale.

► Spirometry and lung volume measurements are recommended for dyspnea evaluation. ► Psychological status assessment is also recommended. ► We show that spirometry and lung volume measurements have limited usefulness. ► We show that dyspnea (MRC score) is not affected by psychological status. ► Statistical analysis shows that specific resistance is a main descriptor of function.