Both cardiac-specific and respiratory-specific measures have been used to assess health status in patients with pulmonary arterial hypertension (PAH). We sought to compare two disease-specific measures and to assess the extent to which they explain changes in general physical health status.
We prospectively enrolled 132 patients with PAH confirmed by right heart catheterization. Cardiac-specific health status was measured using the 21-item Minnesota Living with Heart Failure Questionnaire (LHFQ). Respiratory-specific health status was measured using the 20-item revised Airways Questionnaire 20 (AQ20-R). General physical health status was measured using the Physical Component Summary of the 30-item Short Form 36 (PCS-36). World Health Organization functional class (FC), six-minute walk distance (6MWD), and Borg dyspnea index (BDI) were measured concomitantly. All measures were then repeated at a subsequent visit, and change (Δ) from baseline was calculated for each.
Of 132 patients enrolled, 102 (77%) completed a follow-up visit. LHFQ and AQ20-R at baseline were strongly correlated (r=0.76, p<0.0001). LHFQ and AQ20-R at baseline each correlated well with the PCS-36 (r=−0.69, p<0.0001 and r=−0.57, p<0.0001). Change in LHFQ was associated with ΔPCS-36 (p=0.003). Change in LHFQ remained an independent predictor of ΔPCS-36 (beta=−0.13, p=0.027) after adjusting for age, sex, race, ΔFC, Δ6MWD, and ΔBDI. Change in AQ20-R was associated with ΔPCS-36 (p=0.016). Change in AQ20-R remained an independent predictor of ΔPCS-36 (beta=−0.55, p= 0.022) after adjusting for age, sex, race, and ΔFC, but was no longer significant after taking Δ6MWD, ΔBDI, or ΔLHFQ into account. A comprehensive model including all eight measures explained 24% of the variance in ΔPCS-36 (adjusted R2=0.239, p=0.005).
Cardiac-specific and respiratory-specific measures are responsive to changes in general physical health status. Cardiac-specific health status, as measured by the LHFQ, adds predictive power above that provided by traditional measures of exercise tolerance. In contrast, exercise tolerance measures appear to capture more explanatory power of the AQ20-R, a respiratory-specific health status measure.
Self-reported health questionnaires may be helpful in assessing response to therapy in patients with PAH.
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