Table 4.

Usability performance and summary of the technical log book reported by patients and professionals with respect to the digital health tools supporting the 4 digital health interventions piloted at the Hospital Clinic de Barcelona.

Study	Patients’ experience				Professionals’ experience				Technical log booka
	n	NPSb	SUSc score	n		NPSb	SUSc score
1	33	−3%	78	1		N/Ad	N/A	Recurrent login with a username and a password that are easy to forget (patients).
2	16	31%	67	2		−67%	52	Technology bugs (health professionals) and system enforcement for a random password after reset (patients).
3	19	−21%	56	1		1%	43	Problems connecting the pedometer via Bluetooth with some Android smartphones (patients).
4	31	31%	76	5		−80%	54	Lack of robustness of the multimedia communication channel with some Android smartphones (health professionals).

^aMain reported issues from patients or health professionals.

^bThe Net Promoter Score (NPS) is a known questionnaire used to assess satisfaction with a product, which includes a key question: “How likely is it that you would recommend our system to a family member or friend?” Patients can give an answer ranging from 0 (“not at all likely”) to 10 (“extremely likely”). Individuals scoring 9 or 10 are called “promoters,” individuals scoring 7 or 8 are called “passives” (or neutrals), and individuals scoring 0 to 6 are called “detractors.” The NPS is computed as percent promoters − percent detractors, and ranges from −100% to 100%.

^cThe System Usability Scale (SUS) was developed by John Brooke in 1986 and consists of a 10-item questionnaire scored on a 5-point Likert scale from 0 (strongly disagree) to 5 (strongly agree). The overall score is calculated from the sum of all item scores multiplied by 2.5 and can range from 0 to 100. A system or product that receives a score of 68 or above is considered to have good usability.

^dN/A: not applicable.