Background Breathlessness is the most common symptom reported by patients with pulmonary arterial hypertension (PAH). The Modified Borg Dyspnea Scale (MBS) is routinely obtained during the six-minute walk test in the assessment of PAH patients, but it is not known whether the MBS predicts clinical outcomes such as hospitalizations in PAH. Methods We performed a retrospective study of World Health Organization (WHO) Group 1 PAH patients followed at our center. The dates of the first three MBS and hospitalizations that occurred within three months of a documented MBS were collected. Marginal Cox hazard regression modeling was used to assess for a relationship between MBS and all-cause as well as PAH-related hospitalization. Results A total of 50 patients were included; most (92%) were functional class III/IV, 44% and 65% were treatment-naïve prior to their first MBS and hospitalization, respectively. The first recorded MBS was inversely correlated with the first recorded six-minute walk distance (6MWD) (r = -0.41, P < 0.01) but did not track with WHO functional class (r = 0.07, P = 0.63). MBS did not predict all-cause (hazard ratio [HR], 0.91; 95% confidence interval [CI], 0.76-1.08; P = 0.28) or PAH-related hospitalization (HR, 1.04; 95% CI, 0.89-1.23; P = 0.61), though there was a strong relationship between 6MWD and PAH-related hospitalization ( P = 0.01). These findings persisted after multivariable adjustment. Conclusions Breathlessness as assessed by MBS does not predict all-cause or PAH-related hospitalization. Robust and validated patient-reported outcomes are needed in pulmonary vascular disease.
Keywords: Borg Scale; breathlessness; patient-reported outcomes; pulmonary hypertension; six-minute walk distance.