Comparison of the modified shuttle walk test and cardiopulmonary exercise test in sarcoidosis

Background and objective: Dyspnoea and exercise intolerance are common in sarcoidosis and are often poorly correlated with resting lung function. Measurement of peak exercise capacity is likely to be helpful in assessing and monitoring disease. The aim of this study was to compare the modified shuttle walk test (MSWT) to cardiopulmonary exercise test (CPET) as a measure of peak exercise capacity in sarcoidosis.

Methods: Thirty-three (17 male, mean age 48 years) patients with sarcoidosis completed a standardized exponential exercise protocol cycle ergometer CPET and a single corridor MSWT in random order.

Results: Subjects has a mean forced expiratory volume in 1 s (FEV1) 2.4 L (75.7%predicted), forced vital capacity (FVC) 3.43 L (88.7%predicted) and diffusing capacity for carbon monoxide (DLCO) 20.3 mL/min/mm Hg (71.4%predicted). There was a strong correlation between MSWT distance and peak oxygen uptake (VO2) during CPET (r = 0.87; P < 0.0001), and between maximum heart rate during MSWT and CPET (r = 0.82; P < 0.0001). There was a moderate correlation between FEV1 , FVC and DLCO with MSWT distance (r = 0.55, r = 0.61, r = 0.61, respectively; all P < 0.001) and with peak VO2 (r = 0.62, r = 0.63, r = 0.62, respectively; all P < 0.0001).

Conclusions: Peak VO2 achieved during CPET strongly correlated with MSWT distance. MSWT is a measure of peak exercise capacity in sarcoidosis that does not require equipment and can be readily available in the clinic.