Table 1 Characteristics of the eligible participants in the Sodium and Potassium Study from PURE-China Cohort.

From: Association patterns of urinary sodium, potassium, and their ratio with blood pressure across various levels of salt-diet regions in China

Characteristics

% (n)

Total (n = 41,475)

Heavy-salt regions1 (n = 16,882)

Moderate-salt regions1 (n = 12,851)

Low-salt regions1 (n = 11,742)

Female sex

59.2 (24,546)

60.1 (10,153)

56.8 (7,295)

60.5 (7,098)

Age at recruitment (years, mean ± STD)

51.4 ± 9.4

52.3 ± 8.9

50.9 ± 9.6

50.5 ± 9.8

Education level

    Less than high school graduate

33.7 (13,973)

28.9 (4,870)

39.7 (5,104)

34.1 (3,999)

    High school graduate

57.3 (23,765)

64.7 (10,916)

53.2 (6,840)

51.2 (6,009)

    Some college or more

8.7 (3,608)

6.2 (1,040)

6.8 (868)

14.5 (1,700)

    Missing values

0.3 (129)

0.3 (56)

0.3 (39)

0.3 (34)

Body mass index (BMI, kg/m2, mean ± STD)

24.6 ± 4.0

24.8 ± 4.0

24.6 ± 3.8

24.5 ± 4.0

    <25

54.8 (22,723)

53.6 (9,054)

56.0 (7,190)

55.2 (6,479)

    25-29.9

35.4 (14,677)

36.2 (6,108)

35.32 (4,542)

34.3 (4,027)

     ≥ 30

7.1 (2,955)

7.8 (1,310)

6.4 (821)

7.0 (824)

Missing values

2.7 (1,120)

2.4 (410)

2.3 (298)

3.5 (412)

Waist-to-hip ratio (WHR, mean ± STD)

0.86 ± 0.07

0.86 ± 0.07

0.86 ± 0.06

0.86 ± 0.08

     > 0.9 for men or > 0.85 for women

42.5 (17,605)

41.8 (7,049)

44.2 (5,685)

41.5 (4,871)

Sodium excretion2 (g/day, mean ± STD)

5.7 ± 1.7

5.5 ± 1.6

6.1 ± 1.8

5.3 ± 1.6

    <3

3.5 (1,447)

3.8 (648)

1.9 (243)

4.7 (556)

    3-5

34.3 (14,211)

36.0 (6,082)

25.7 (3,299)

41.1 (4,830)

     > 5

62.3 (25,817)

60.1 (10,152)

72.4 (9,309)

54.1 (6,356)

Potassium excretion2 (g/day, mean ± STD)

2.1 ± 0.5

2.1 ± 0.5

2.1 ± 0.5

2.1 ± 0.5

    <1.9

36.5 (15,148)

37.7 (6,356)

34.8 (4,473)

36.8 (4,319)

    1.9-2.5

44.9 (18,625)

45.5 (7,675)

45.0 (5,778)

44.1 (5,172)

     > 2.5

18.6 (7,702)

16.9 (2,851)

20.2 (2,600)

19.2 (2,251)

Ratio for sodium vs. potassium2 (mean ± STD)

2.8 ± 0.8

2.7 ± 0.7

3.0 ± 0.8

2.6 ± 0.7

    <2.0

15.1 (6,244)

15.8 (2,660)

10.2 (1,314)

19.3 (2,270)

    2.0-3.0

51.7 (21,453)

52.6 (8,880)

46.8 (6,011)

55.9 (6,562)

     > 3.0

33.2 (13,778)

31.6 (5,342)

43.0 (5,526)

24.8 (2,910)

Creatinine excretion3 (g/day, mean ± STD)

1.2 ± 0.3

1.2 ± 0.3

1.3 ± 0.3

1.2 ± 0.3

Systolic blood pressure (mmHg, mean ± STD)

133.5 ± 22.0

132.3 ± 21.6

137.0 ± 22.5

131.2 ± 21.7

    <120

28.6 (11,856)

30.2 (5,097)

22.3 (2,864)

33.2 (3,895)

    120-139

38.0 (15,764)

38.2 (6,449)

38.8 (4,981)

36.9 (4,334)

     ≥ 140

33.4 (13,855)

31.6 (5,336)

39.0 (5,006)

29.9 (3,513)

Diastolic blood pressure (mmHg, mean ± STD)

82.8 ± 12.3

82.3 ± 11.9

84.1 ± 12.7

82.2 ± 12.2

    <60

1.3 (552)

1.3 (222)

1.4 (177)

1.3 (153)

    60-89

72.7 (30,148)

74.4 (12,556)

68.7 (8,828)

74.6 (8,764)

     ≥ 90

26.0 (10,775)

24.3 (4,104)

35.7 (3,846)

24.1 (2,825)

Self-reported hypertension or had blood pressure medication or blood pressure ≥ 140/90 mmHg

    No

56.8 (23,555)

57.2 (9,664)

52.6 (6,759)

60.7 (7,132)

    Yes

43.2 (17,920)

42.8 (7,218)

47.4 (6,092)

39.3 (4,610)

Self-reported diabetes or fasting glucose >7.0 mmol/L

    No

90.8 (37,661)

89.6 (15,124)

92.3 (11,862)

90.9 (10,675)

    Yes

9.2 (3,814)

10.4 (1,758)

7.7 (989)

9.1 (1,067)

Self-reported stroke

    No

97.9 (40,596)

97.7 (16,488)

98.1 (12,604)

98.0 (11,504)

    Yes

1.9 (785)

2.1 (362)

1.6 (200)

1.9 (223)

Missing values

0.2 (94)

0.2 (32)

0.4 (47)

0.1 (15)

Self-reported angina, heart attack or coronary artery diseases

    No

93.7 (38,855)

94.6 (15,968)

92.7 (11,915)

93.4 (10,972)

    Yes

6.3 (2620)

5.4 (914)

7.3 (936)

6.6 (770)

Tobacco use

    Never

72.3 (30,003)

69.3 (11,702)

77.4 (9,944)

71.2 (8,357)

    Former

4.7 (1,964)

4.4 (748)

3.6 (468)

6.4 (748)

    Current

21.8 (9,060)

24.6 (4,153)

18.4 (2,359)

21.7 (2,548)

    Missing values

1.1 (448)

1.7 (279)

0.6 (80)

0.8 (89)

Alcohol consumption

    Never

75.4 (31,290)

73.3 (12,376)

81.4 (10,454)

72.0 (8,460)

    Former

3.2 (1,329)

2.6 (433)

2.2 (285)

5.2 (611)

    Current

20.8 (8,620)

23.1 (3,902)

16.2 (2,081)

22.5 (2,637)

    Missing values

0.6 (236)

1.0 (171)

0.2 (31)

0.3 (34)

Levels of physical activities

    Low

12.2 (5,049)

12.1 (2,036)

13.7 (1,763)

10.7 (1,250)

    Medium

41.7 (17,311)

43.8 (7,398)

43.9 (5,646)

36.3 (4,267)

    High

41.6 (17,250)

40.8 (6,886)

37.2 (4,779)

47.6 (5,585)

Missing values

4.5 (1,865)

3.3 (562)

5.2 (663)

5.5 (640)

Total cholesterol (mmol/L, mean ± STD)

4.7 ± 1.0

4.7 ± 1.0

4.6 ± 1.0

4.8 ± 1.1

    ≥6.47

4.0 (1,642)

3.4 (576)

3.4 (442)

5.3 (624)

Triglycerides (mmol/L, mean ± STD)

1.6 ± 1.2

1.5 ± 1.2

1.6 ± 1.2

1.6 ± 1.1

    ≥4.50

2.4 (1,013)

2.5 (423)

2.6 (328)

2.2 (262)

LDL cholesterol (mmol/L, mean ± STD)

2.6 ± 0.8

2.6 ± 0.8

2.6 ± 0.8

2.6 ± 0.9

    >4.14

2.9 (1,199)

2.5 (427)

2.8 (362)

3.5 (410)

HDL cholesterol (mmol/L, mean ± STD)

1.4 ± 0.4

1.4 ± 0.4

1.3 ± 0.3

1.4 ± 0.4

    <0.91

8.8 (3,640)

9.2 (1,552)

10.3 (1,323)

6.5 (765)

Fasting glucose (mmol/L, mean ± STD)

5.6 ± 1.6

5.8 ± 1.5

5.1 ± 1.7

5.7 ± 1.4

    >7.00

7.6 (3,157)

8.7 (1,467)

6.1 (787)

7.7 (903)

  1. Note: STD, standard deviance; LDL, low-density lipoprotein; HDL, high-density lipoprotein;
  2. 1Per National Diet Salt Intake in 200228, PURE-China centers were classified three salt-diet regions: heavy-salt regions (>8 grams of daily salt intake) included Beijing, Jiangsu Province, Jiangxi Province, and Liaoning Province; moderate-salt regions (7 to 8 grams) included Qinghai Province, Shaanxi Province, and Shandong Province; low-salt regions (<7 grams) included Inner Mongolia, Sichuan Province, and Yunnan Province, Shanxi Province, and Xinjiang Province.
  3. 2Estimated excretion was calculated by a fasting morning urine specimen on the basis of the Kawasaki formula18;
  4. 3Creatinine excretions were determined according to a formula including age, sex, weight, and height, which also was used in Kawasaki formula to estimate sodium and potassium excretion.
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