Table 2.

Mean absolute error compared with reference device, and failure rate of tested monitors (n = 327) by length of time in service^a

Years in hservice	Monitors, n	Failing monitors, n (%)^b	Cumulative failing monitors, n (%)^c	MAE, mmHg (95% CI)
0–1	41	0	0	0.63 (0.55 to 0.72)
>1–2	50	5 (10)	5 (5)	0.73 (0.66 to 0.81)
>2–3	36	1 (3)	6 (5)	0.62 (0.53 to 0.71)
>3–4	28	2 (7)	8 (5)	0.80 (0.70 to 0.90)
>4–5	29	6 (21)	14 (8)	1.03 (0.93 to 1.13)
>5–6	20	7 (35)	21 (10)	1.44 (1.32 to 1.56)
>6–7	14	2 (14)	23 (11)	0.88 (0.73 to 1.02)
>7–10	54	15 (28)	38 (14)	1.18 (1.10 to 1.25)
>10	7	2 (29)	40 (14)	1.29 (1.08 to 1.50)
Not stated/monitor owner unable to remember	48	6 (13)	n/a	0.89 (0.81 to 0.97)

↵a Four monitors could not be tested fully but should be counted as failures.
↵b Percentage of total monitors per years-in-service classification.
↵c Percentage of cumulative total of monitors per years-in-service classification and shorter lengths of service. MAE = mean absolute error.