Table 1.

Model results from separate models of engagement with an mHealth intervention (defined as intervention use) and time to dropout and the joint model of engagement and time to dropout.

		Separate models		Joint model
		Parameter estimate	P value	Parameter estimate	P value
Longitudinal engagement outcome
	Intercept (β0)	4.28 (0.13)	<.001	4.05 (0.10)	<.001
	Study week 1 (β1)	−0.13 (0.014)	<.001	−0.14 (0.014)	<.001
	Study week 2 (β2)	0.0029 (0.0005)	<.001	0.0021 (0.0006)	.001
Time-to-dropout
	Age (γ1)	0.084 (0.14)	.58	−0.021 (0.13)	.87
	Male (γ2)	0.073 (0.12)	.54	−0.10 (0.10)	.32
	Black versus white (γ3)	0.058 (0.14)	.67	−0.097 (0.13)	.46
	Hispanic versus white (γ4)	0.12 (0.19)	.51	0.15 (0.18)	.41
	Other versus white (γ5)	0.27 (0.17)	.10	0.11 (0.17)	.49
	Longitudinal engagement association (α)			−0.26 (0.022)	<.001