Table 4.

Concordance between SD of SBP from 3 to 20 SBP measurements

Number of BP measurement	Mean SD of SBP, mm Hg	Delta, mm Hg	r	ICC (95% CI)	P value	Number of patients
20	13.4±3.7	Ref	Ref	Ref	Ref	1344
16	13.3±4.0	0.1	0.94	0.97 (0.96 to 0.97)	<0.001	1381
12	13.1±4.2	0.3	0.82	0.90 (0.89 to 0.91)	<0.001	1396
10	12.9±4.4	0.5	0.77	0.87 (0.85 to 0.88)	<0.001	1399
9	12.9±4.5	0.5	0.74	0.84 (0.82 to 0.86)	<0.001	1401
8	12.8±4.7	0.6	0.71	0.82 (0.80 to 0.84)	<0.001	1403
7	12.7±4.9	0.7	0.66	0.78 (0.76 to 0.80)	<0.001	1403
6	12.6±5.2	0.8	0.62	0.74 (0.71 to 0.77)	<0.001	1403
5	12.6±5.6	0.8	0.56	0.68 (0.65 to 0.72)	<0.001	1403
4	12.2±6.0	1.2	0.47	0.60 (0.55 to 0.64)	<0.001	1403
3	11.5±6.9	1.9	0.34	0.45 (0.39 to 0.51)	<0.001	1403

Delta, difference in SD of SBP compared with SD of SBP calculated from 20 BP measurements; ICC, intraclass correlation coefficient; r, Pearson’s coefficient; SBP, systolic blood pressure.