Exploration of the minimal clinically important difference value of the 3-min simulated pedal motion in patients with chronic obstructive pulmonary disease: A self-controlled prospective clinical trial

Abstract

Background: To help elderly patients with severe or very severe chronic obstructive pulmonary disease (COPD) with pulmonary rehabilitation, we have developed Zheng's supine rehabilitation exercise (ZSRE). Currently, none of the terminal or critically ill patients with severe exercise limitation can complete the 6-min walking distance (6MWD) and cardiopulmonary exercise testing (CPET). Methods: In this study, we discuss the definition of the standardized 3-min simulated pedal motion (3MSPM) test and its operational specifications. Also, we evaluate the minimal clinically important difference (MCID) value of the 3MSPM. Results: The results showed that the mMRC score of COPD patients with acute exacerbation of dyspnea was progressively reduced from the second day of respiratory rehabilitation, and the difference between the first and seventh days was statistically significant (p < 0.000, χ2 = 176.664). 6MWD increased progressively, and the difference between 6MWD on day 1–7 was statistically significant (p = 0.024, F = 2.443). The difference between 3MSPM on day 1–7 was also statistically significant (p < 0.000, F = 4.481). Further analysis showed that 6MWD was negatively correlated with mMRC (p < 0.000, OR = −0.524). 3MSPM was positively correlated with 6MWD (p < 0.000, OR = 0.640) but negatively correlated with mMRC (p < 0.000, OR = −0.413). There is a linear regression relationship between 6MWD and 3MSPM, that is, 6MWD = 14.151 + 0.301 * 3MSPM, adjusted R2 = 0.401. Conclusion: Based on the regression equation, 3MSPM can predict 6MWD, and it can be used as a simple exercise endurance method to evaluate patients with safety hazards in underground activities or who cannot complete the 6MWD test. The minimum clinically important difference value is increased by 23.