Table 2.

Methods for measuring adherence to e-therapy as reported by included studies (n = 69)

Measure of adherence	Number of times reported
Logins to program	36
Module completion	31
Time spent online	18
Completion of a predefined activity such or use of an online tool	16
Posts made	9
Pages viewed	5
Replies to emails	6
Forum visits	1
Use of online tools	1
Self-reported completion of offline activities	1
Print requests made	1

Of the 69 studies that reported measuring adherence, approximately half did so by measuring logins and/or completion of modules. Only a quarter of the 69 included studies reported 1 or more of the other potential measures of adherence. The reporting of module completion was more common in studies where the target behavior was psychological health or well-being (25/40, 63%) rather than physical health (6/29, 21%) (n = 69, χ² ₁ = 11.9, P <.001). Conversely, login reporting was more common in studies where the target behavior was related to physical health (23/29, 79%) rather than psychological health (13/40, 33%) (n = 69, χ² ₁ = 14.8, P ≤.001).