Table 1.

Baseline characteristics of subjects

	1st (n=248)	2nd (n=129)	3rd (n=346)	4th (n=196)	5th (n=336)	P
Age (years)	67.4 ± 10.2	68.2 ± 8.9	68.7 ± 9.5	72.7 ± 9.5	73.8 ± 9.5	<0.001
Male sex (%)	37.5	40.3	32.1	39.3	42.6	0.07
Body mass index (kg/m2)	24.4 ± 3.5	24.0 ± 3.7	24.1 ± 3.6	23.6 ± 3.2	23.5 ± 3.4	0.009
Smoking (%)	22.6	25.6	18.5	23.5	23.2	0.41
Diabetes (%)	26.6	32.6	25.4	23.0	17.3	0.005
Cholesterol (mg/dl)	204 ± 36	200 ± 34	204 ± 34	199 ± 34	198 ± 35	0.08
Triglycerides (mg/dl)	143 ± 82	144 ± 71	139 ± 76	128 ± 61	128 ± 76	0.02
Serum creatinine (mg/dl)	0.85 ± 0.22	0.83 ± 0.21	0.85 ± 0.23	0.88 ± 0.23	0.86 ± 0.22	0.22
Clinic SBP (mmHg)	160 ± 20	158 ± 21	160 ± 19	160 ± 18	163 ± 19	0.10
Clinic DBP (mmHg)	88 ± 13	87 ± 13	88 ± 14	88 ± 13	89 ± 14	0.72
24-hour SBP (mmHg)	140 ± 17	140 ± 18	138 ± 17	137 ± 15	139 ± 17	0.30
24-hour DBP (mmHg)	80 ± 10	80 ± 10	78 ± 10	78 ± 9	78 ± 10	0.05
24-hour PR (beats/min)	72 ± 7	71 ± 8	69 ± 8	69 ± 8	69 ± 8	<0.001
Awake SBP (mmHg)	146 ± 18	147 ± 20	145 ± 18	143 ± 15	146 ± 18	0.30
Awake DBP (mmHg)	83 ± 10	83 ± 11	82 ± 11	81 ± 9	82 ± 11	0.29
Awake PR (beats/min)	76 ± 8	75 ± 9	74 ± 9	74 ± 9	75 ± 9	0.04
Sleep SBP (mmHg)	128 ± 18	129 ± 18	126 ± 19	127 ± 18	129 ± 18	0.35
Sleep DBP (mmHg)	73 ± 10	73 ± 11	72 ± 11	72 ± 10	73 ± 10	0.38
Sleep PR (beats/min)	62 ± 9	62 ± 8	60 ± 8	60 ± 8	61 ± 8	0.03
Night-day SBP ratio	0.88 ± 0.09	0.88 ± 0.08	0.88 ± 0.09	0.89 ± 0.09	0.89 ± 0.09	0.54
Non-dipping pattern (%)	37.1	40.3	40.5	39.8	44.6	0.47
Risers (%)	8.1	4.7	6.9	9.2	8.0	0.61

Data are shown as percentage or mean±SD.

SBP, systolic blood pressure; DBP, diastolic blood pressure; PR, pulse rates.

1st: 4.0 – 7.4hrs; 2nd: 7.5–7.8 hrs; 3rd: 8.0–8.8 hrs; 4th: 9.0 – 9.4 hrs; 5th: 9.4–13.0hrs

P-values are based on a 1-way ANOVA for the continuous measures, and the chi-square test of independence for dichotomous measures.