Table 2.

Mean (SD) participant ratings of interface and system usability.

Variable (range 0-100)	All (n=20)	Intervention arm (n=9)	Monitoring-only arm (n=11)	P value
Phone—ease of use	93.1 (7.2)	91.1 (8.3)	94.6 (6.1)	.29
Watch—ease of use	91.6 (12.6)	94.4 (5.1)	89.3 (16.3)	.38
Phone—pleasantness	87.7 (13.7)	90.0 (13.2)	85.8 (14.5)	.51
Watch—pleasantness	87.9 (14.9)	91.7 (7.9)	84.8 (18.7)	.32
Overall satisfaction	88.5 (9.1)	91.3 (5.5)	86.2 (11.0)	.22
System Usability Scale	85.1 (11.5)	83.6 (9.2)	86.4 (13.5)	.61