Analysis methods
SECONDARY
The primary analysis will evaluate the change in distance walked during the 6MWT from baseline to 6 months based on the intention-to-treat population. The analysis will be performed using a linear mixed-effect model accounting for clustering at the center level (random effect) and adjusted for baseline distance walked during the 6MWT, age, sex, and NYHA class (fixed effects). The intervention effect (adjusted value for change in intervention minus change in control) will be reported as the mean (95% CI) and associated The secondary analyses will evaluate changes in the 6MWT distance from the baseline to 3- and 12-month time points and changes in secondary outcomes from the baseline to all available time points (Table Several exploratory subgroup analyses are planned to assess the differential effect of the intervention on patients (1) participating before, during, and after the COVID-19 pandemic and (2) allocated to either of the two research nurses providing phone support.