Cardiopulmonary exercise testing (
CPET) plays an important role in the assessment of functional capacity in patients with
interstitial lung disease. The aim of this study was to identify
CPET measures that might be helpful in predicting the vital capacity and diffusion capacity outcomes of patients with thoracic
sarcoidosis. A longitudinal study was conducted on 42 nonsmoking patients with thoracic
sarcoidosis (median age = 46.5 years, 22 females). At the first evaluation, spirometry, the measurement of single-breath
carbon monoxide diffusing capacity (D LCOsb) and
CPET were performed. Five years later, the patients underwent a second evaluation consisting of spirometry and D LCOsb measurement. After 5 years, forced vital capacity (FVC)% and D LCOsb% had decreased significantly [95.5 (82-105) vs 87.5 (58-103) and 93.5 (79-103) vs 84.5 (44-102), respectively; P < 0.0001 for both]. In
CPET, the peak
oxygen uptake, maximum respiratory rate, breathing reserve, alveolar-arterial
oxygen pressure gradient at peak exercise (P(A-a)O2), and Δ SpO2 values showed a strong correlation with the relative differences for FVC% and D LCOsb% (P < 0.0001 for all). P(A-a)O2 ≥22 mmHg and breathing reserve ≤40% were identified as significant independent variables for the decline in pulmonary function. Patients with thoracic
sarcoidosis showed a significant reduction in FVC% and D LCOsb% after 5 years of follow-up. These data show that the outcome measures of
CPET are predictors of the decline of pulmonary function.