Table 3.

Facilitators and barriers of eHealth interventions in MSM population

Components	Considerations
Technology and system	Interventions could be implemented within existing technical systems that could reach MSM without burden of enrolment process [73] Developed on html platform that could not adjust to mobile phone or tablet, reducing the chance to widespread the intervention to the target population [62] Electronic delivery system did not operate automatically [46, 86] or the intervention was implemented manually [63], that could reduce the opportunities to access messages
Content and format
Theory and contents	Combine various behaviour change techniques/theories could increase effects of intervention [52] Not using individualized messages [55, 59, 69, 79, 86] or static content of messages reduced the effects of intervention [53, 62] Too short 69 or too long videos could be a potential barrier [56]
Workload and length of intervention	A multi-session intervention is acceptable and possibly even engaging [46] Insufficient time for intervention might result in ineffective outcomes [52, 89] Long-term follow up increased loss to follow up [56]
Mode of presentation	Engaging, highly interactive, fun; dominance by visual instead of verbal; written in a real-world direct peer-to-peer style; allow to compare with other peers [62, 81] Using multiple methods (video, animation, games, etc.) and user-friendly interface allowed for individuals with different learning styles to be impacted by the content [59, 62] Participants might not read contents carefully 86 or become bored with viewing and interacting with the same material across the intervention [46] If sessions were boring or not engaging, participant might take more time to complete [46, 62]
Preparation
Staff	Interventionist was well trained and a natural helper could gain the trust and respect from participants [59, 73] Developing and informing tailored messages required well-trained providers/interventionists [48, 59, 79] Clinicians forgot to send SMS reminder reduced the opportunities to access messages in MSM [66]
Incentives	Incentives did not play a role in retention [74], however, no incentives might reduce the retention [60] Increase reimbursement did not affect retention [46]
Implementation
Recruitment	Place recruitment banner ad on exclusively gay sex sites increased the rate of click compared to on the public service banners [74, 81, 88] Limited recruitment sources might lead to insufficient sample size [74]
Relationship	Building rapport increased the level of retention [103] Promotion of interaction between MSM and facilitators could achieve and sustain an intervention effect and promote higher retention rates [73] Lack of interpersonal relationship could lead to be ineffective [86]
Retention	Strong retention protocol; interactive engaging activities; appropriate visual learning elements; use realistic sexually explicit images could increase retention rate [74, 81]