Power and sample size for multistate model analysis of longitudinal discrete outcomes in disease prevention trials

For clinical trials where participants pass through a number of discrete health states resulting in longitudinal measures over time, there are several potential primary estimands for the treatment effect. Incidence or time to particular state commonly used outcomes but choice may not be obvious and these do make full use assessments. Multistate models have been developed some diseases conditions with purpose understanding their natural history secondary analysis understand mechanisms action treatments. There is little published on multistate as method implications design features, such assessment schedules. We illustrate methods via data from motivating example; Phase III trial pressure ulcer prevention strategies. clarify possible that might considered we show, simulation study, under circumstances sample size could reduced by half using model based analysis, without adversely affecting power trial.