The Roles of Adherence and Usage Activity in Adolescents' Intervention Gains During Brief Guided Online Acceptance and Commitment Therapy.

Objective: This study investigated the roles of adherence and usage activity in adolescents' (n = 161) gains during a 5-week web intervention program based on acceptance and commitment therapy (ACT).

Method: Program adherence was calculated as adherence percentage in relation to intended usage, whereas completion percentage, usage time, and usage weeks were used as indicators for usage activity. Subjective well-being was measured by self-reported life satisfaction and stress before and after the intervention.

Results: First, regression analysis results showed that higher adherence predicted an increase in life satisfaction during intervention. Second, three subgroups of adolescents were identified using K-means cluster analysis in regard to adherence, usage activity and intervention gains: (1) "Adhered, committed users with relatively large intervention gains" (35%), (2) "Less committed users with no intervention gains" (42%), and (3) "Non-committed users with no intervention gains" (23%). The results showed that the highest gains from the Youth Compass intervention program are most likely obtained when the program is used as intended in its design. In addition, time investment and engagement in doing exercises seem as important as filling the minimum adherence criterion.

Conclusions: The results support the feasibility of ACT-based web intervention programs in promoting adolescent well-being, although more attention should be paid to motivating adolescents to commit to them and invest enough time in them.