Implementation of an Internet-based psychological intervention for the treatment of mild depression in primary care: A Hybrid Effectiveness-implementation approach

Background Depression is a significant global challenge. Particularly in Spain, depression in Primary Care (PC) settings is prevalent and inadequately addressed. Online interventions, such as "Smiling is Fun", an online Cognitive Behavioral program, offer promising solutions given its scalability and accessibility. However, successful implementation in real-world settings requires identifying and addressing contextual barriers. This study aims to implement "Smiling is Fun" while assessing its effectiveness and the determinants influencing its implementation. Methods The study employed a Hybrid Effectiveness-Implementation Type II approach using a Stepped-Wedge Cluster Randomized-Controlled Trial methodology. Six sites were randomized into three clusters, each undergoing treatment conditions for 16 weeks. Patients were recruited by health professionals in PC settings. Results The intervention effectively reduced depressive symptoms and improved positive affect. Participants generally had a positive attitude towards internet interventions, although there was a slight increase in concerns regarding professional contact. Overall satisfaction among participants who completed the intervention was moderately high, but problems with treatment adherence were observed. Professionals demonstrated a willingness to adopt the program, with generally high readiness to implement the intervention. Nevertheless, some important barriers, such as high levels of stress, insufficient learning time, and personnel changes were highlighted. Discussion "Smiling is Fun" proved effective in addressing mental health states and depressive symptomatology, with positive perceptions from both professionals and patients. However, barriers need to be addressed, particularly in fostering inclusion in the PC workflow system and promoting patient adherence. Despite limitations, the study underscores the potential of online interventions to improve mental healthcare accessibility. Trial registration: https://clinicaltrials.gov/study/NCT05294614 (23/03/2022)