The study was powered to detect an effect size of a 5-point increase in the Medical Health Survey Short-Form 36 (SF-36) on the mental component score (MCS) in the intervention group at 12 months post-ICU. Power calculation was based on an expected distribution of MCS from a matched population with a mean of 36.7 (SD 11.7) from a similar study. With a statistical power of 80% and significance level of 0.05, we estimated that 86 relatives were needed in each group to complete follow-up.