Primary estimand attributes
death, dementia
EVENTS, EVENT

Treatment: MI added to SC compared to SC alone (control), allocation by randomisation.Population: Adults with diagnosed dementia who are residing at home with a caregiver (e.g. sibling, spouse, adult child) who is not paid to deliver care. Full details of the inclusion and exclusion criteria are provided in the protocol [Variable: NPI-Q severity at 90 days post-randomisation.Intercurrent events: Possible intercurrent events are outlined below and will be handled using the treatment policy strategy except for death of the PwD for which the composite strategy will be used by assigning the worst-possible NPI-Q score (i.e. 36). Where possible, outcome data will be collected after each of these intercurrent events occur. If no data is collected after an intercurrent event, we will assume that the participant’s outcome after the intercurrent event will be similar to that of all other participants (see details in reporting and methods for missing data).A dyad receiving a different treatment to what they were allocated toRelocation of PwD to a care homeA dyad no longer cohabitatingA change in primary carerDeath of either the PwD or primary carerNew medication taken by the PwD or CG (any post-baseline that will affect the trial outcome; see section on concurrent medications for details)Hospitalisation of either the PwD or CGUnplanned or planned surgery or dental work for either the PwD or CGCOVID-19 without hospitalisation of either the PwD or CGPopulation-level summary: mean difference in NPI-Q severity between arms (MI + SC and SC alone).The number and percentage of dyads who had intercurrent events will be described overall and by treatment arm.