Sample size
To examine the power to detect clinically relevant intervention-related changes in HrQOL outcomes, we simulated normally distributed pre and 16-week post intervention HrQOL scores with no changes in mean HrQOL in the control group and an absolute increase of at least 8 points in the MCS or PCS (from pre to post)in the intervention, a within-group standard deviation (SD) of 10.0 and positive correlation between HrQOL measurements from the same person such that Pearson’s rho = 0.70. Our hypothesized effect size was based on studies showing that a change of 8 points or more in PCS has been associated with a clinically significant decrease in hospitalizations and mortality [