Participation Definition
An ITT framework would consider all patients randomized to the intervention group as participants. We developed a participation definition for the purposes of reanalysis that acknowledged varied participation levels by categorizing intervention group enrollees as engaged participants or nonparticipants. Engaged participants were individuals in the treatment arm who met at least 2 of the 3 following criteria: received at least 3 intervention hours during the first 2 weeks of enrollment, had contact with staff at least once per week for 4 of the initial 6 weeks, were retained in the program for 60 days (half of the average treatment length) or graduated within that timeframe.The thresholds were chosen based on each measure’s distribution, together with the logical design of the intervention. The beginning period of the intervention was considered crucial as staff collected information, conducted home visits, designed care plans with patients, and built relationships, and the intervention was designed in a continuous way such that patients were expected to be engaged at least once weekly. Results of sensitivity analyses using different thresholds for the measures of engaged participation are shown in eAppendix 2 in 