Statistical Power
Following the interim analysis, power was recalculated using an expected 438 participants (see An interim intention-to-treat (ITT) analysis, overseen by the IDMC, considered closing trial arms based on: (1) Treatment engagement: > 50% of individuals receiving less than 5 therapy hours, (2) Cost-effectiveness: > £500 for a one-point increase in cognition or one hour of structured activity (a reasonable cost adopted from a previous trial