Table 3.

Participant engagement and retention strategies.

Intervention type, reference		Participants, n	Intervention		Dropouta, n (%)		Reported reasons to drop out	Financial or material support	Access to the technology
			Duration	Follow-up
Smartphone
	Thompson et al [42], 2020	60	28 days	N/Ab	20 (33)		16 discharged; 1 incarcerated; 1 hospitalized; 1 self-withdrew; 1 relocated	US $25 to US $50 gift cards+smartphone or US $100 gift card		Researchers provided the smartphones
	Schueller et al [19], 2019	35	1 month	N/A	15 (43)		Unclearc	Phone service and data		Researchers provided the smartphones
	Glover et al [40], 2019	100	6 months	N/A	81 (81)		Unclear	Smartphone+US $5 gift card		Researchers provided the smartphones
	Sheoran et al [41], 2016	6	One time	N/A	N/A		N/A	US $100 gift card		Researchers provided the smartphones. A total of 83% (5/6) participants already owned a smartphone
	Chao et al [36], 2017	24	1 month	N/A	Unclear		Unclear	Unclear		Researchers provided the smartphones
	Karnik et al [46], 2017	20	Unclear	Unclear	N/A		N/A	Unclear		Researchers provided the smartphones
	Leonard et al [43], 2018	49	Variable (6-8 months)	N/A	9 (18)		4 discharged; 4 technology problem; 1 did not use the ICTd	US $90 stipend		Researchers provided the smartphones
	Linnemayr et al [38], 2021e	77	6 weeks	3 months	11 (14)		Unclear	US $65		Participants’ phone
	Tucker et al [39], 2020e	28f	1 week	N/A	2 (20)f		Unclear	Unclear		Participants’ phone
Other ICTs
	Medalia et al [45], 2017	91	26 weeks	1 month	69 (76)		Baseline to week 26: 25 loss of interest; 14 moved; 17 scheduling conflict; 7 discharged; 4 withdrawn; 2 legal issues	Reimbursed for public transportation cost		Researchers provided the computers
	Chavez et al [44], 2020	30	One time	1-3 days	1 (3)		1 did not return	US $50		Researchers provided the headset
	Archie et al [47], 2018	55	Unclear	Unclear	Unclear		Unclear	Unclear		Unclear

^aPercentage of dropouts: participants who were assessed at baseline and were lost to follow-up.

^bN/A: not applicable.

^cUnclear: authors did not provide sufficient or any information.

^dICT: information and communication technology.

^eLinnemayr et al [38] and Tucker et al [39] reported the same population.

^fThe sample that was analyzed in Tucker et al [39] was included and analyzed in Linnemayr et al [38]. Dropout percentage was calculated from the 10 participants who were included in the intervention, the rest (18 participants) participated in focus groups and were not counted for dropout proportions.