Table 5.

Major usability issues related to the personalization features and modifications made to overcome them.

Usability issues				Changes implemented
Personal data reuse preferences
	Iteration 1
		Withdrawing consent for study participation instead of changing preferences on data sharing	Introduce “Withdraw” buttons to undo earlier choices Introduce a confirmation dialogue when informed consent for study participation was requested to be withdrawn
	Iteration 2
		Withdrawing consent for study participation instead of changing preferences on data sharing	Present the actions of changing preferences on data sharing and withdrawing consent for study participation on 2 distinct interfaces
	Iteration 3
		Withdrawing consent for study participation instead of changing preferences on data sharing	N/Aa
Changing preferences regarding study results
	Iteration 1
		Consulting the “Findings and results” information section instead of clicking the “Manage” button under the “Study preferences” section	Change the title of the section from “Study preferences” to “Study results” Change the text label of the “Manage” button to “Manage your preferences”
	Iteration 2
		Consulting the “Findings and results” information section instead of clicking the “Manage” button in the “Study preferences” section	N/A
New informed consent form version
	Iteration 1
		Not being able to recognize the sections containing changes Being confused about how the changes in a new informed consent form version are displayed	Highlight the information sections containing changes in orange Put the text of the previous informed consent form version on the left of the interface while only showing modifications on the right
	Iteration 2
		Not being able to recognize the sections with changes	Add a “Changed” label in the buttons of the information sections

^aN/A: not applicable.