Optimizing the context of support of web-based self-help in individuals with mild to moderate depressive symptoms: A randomized full factorial trial.

Web-based self-help programs for individuals with depressive symptoms are efficacious. Differences in effect sizes and adherence rates might be due to contextual factors. This randomized factorial trial investigated the effects of four potentially supportive contextual factors on outcome and adherence. Two factors were provided through human contact (guidance and a diagnostic interview), and two factors were provided without human contact (a motivational interviewing module and automated emails). We recruited 316 adults with mild to moderate depressive symptoms (Patient Health Questionnaire-9 score: 5-14). All participants received access to a problem-solving therapy program. Participants were randomized across the four experimental factors (present or absent), resulting in a 16-condition design. The primary outcome was depressive symptoms 10 weeks after baseline. The secondary outcome was program adherence. Overall, results showed significant symptom reduction for the primary depression measure (Cohen's d = 0.38-0.91). Guided participants showed significantly less severe symptoms of depression at post-treatment (d = 0.15) and higher treatment adherence (d = 0.53). At follow-up, these differences were no longer present. The remaining three factors did not influence primary outcome and adherence. These findings indicate that guidance leads to a faster reduction of depressive symptoms and higher treatment adherence.