Construct	Items	Source
Health Professional Encouragement	Usage of MyChart is encouraged by my healthcare professional team (e.g., healthcare provider/doctor, office staff, practice administrators).	Zhou and George (2001)
	My healthcare professional team endorses MyChart usage.
	My healthcare professional team supports involvement in MyChart usage.
Security Concerns	I am concerned about submitting information on MyChart because of the potential for security breaches.	Dinev and Hart (2006)
	I am concerned that information on MyChart could be accessed by unauthorized parties who hack into the system.
	I am concerned about submitting information on MyChart because others might hack into the system.
Continuous Use Intention	I intend to continue using MyChart in the future.	Kock et al. (2016); Lowry et al. (2015)
	I will always try to use MyChart in my daily life.
	I plan to continue to use MyChart frequently.
Deep Structure Usage	When I was using MyChart, I used features that helped me to see my lab results.	Burton-Jones and Straub Jr. (2006)
	When I was using MyChart, I used features that helped me to request a refill.
	When I was using MyChart, I used features that helped me to send a message to my provider.
	When I was using my MyChart, I used features that helped me to track my health progress over time.
	When I was using my MyChart, I used features that helped me to learn more about my medical condition.
	When I was using my MyChart, I used features that helped me to manage my healthcare.