Table 3.

Factors associated with risk of attrition among the online participants in the initial phase

	Model A: discontinuation as event of interest, withdrawal as competing event		Model B: withdrawal as event of interest, discontinuation as competing event
	Beta	Hazard ratio	Beta	Hazard ratio
Age at baseline (per 10 years increase)	−0.15	0.86	0.10	1.11
Frequency of Internet usage	not selected in this model
Daily			Reference	Reference
Less than daily			0.28	1.32
PSS score (per 1 point increase)	0.04	1.04	not selected in this model
Time between invitation and return of the filled informed consent form (per week)	0.05	1.05	not selected in this model
Had to be reminded to fill in the first online questionnaire (A)			not selected in this model
Yes	0.37	1.44
No	Reference

Variables were selected using the least absolute shrinkage and selection operator method in competing risks regression

PSS: perceived stress scale (score ranges from 0 [very low stress level] to 16 [very high stress level])