Sample size and power calculations
The sample size was calculated based on two co-primary end points: carer preparedness and carer distress at 4 months after randomisation. Using a 5% significance level, two-tailed testing of differences between two independent groups (usual care and intervention), a sample of 64 patients per group (128 total), has 80% power to detect group differences of 0.5 SDs (moderate effect size; considered clinically significant) for carer preparedness [