TABLE 1.
Characteristics of participants, 1991–20091
| 1991 | 1993 | 1997 | 2000 | 2004 | 2006 | 2009 | |
| No. of subjects | 7337 | 6958 | 7241 | 7940 | 7250 | 6826 | 6932 |
| Sample participated previously (%)2 | 85.0 | 60.5 | 78.4 | 78.6 | 88.2 | 77.7 | |
| Replenishment sample (%) | 15.0 | 39.5 | 21.6 | 21.4 | 11.8 | 22.3 | |
| Age (y) | 37.4 ± 11.03 | 37.9 ± 10.9 | 38.8 ± 10.8 | 40.1 ± 10.5 | 42.3 ± 10.4 | 43.3 ± 10.2 | 43.5 ± 10.6 |
| 20–29 y (%) | 32.2 | 28.8 | 26.0 | 20.7 | 15.0 | 12.0 | 13.6 |
| 30–39 y (%) | 28.9 | 29.2 | 26.9 | 28.8 | 25.8 | 24.9 | 22.3 |
| 40–49 y (%) | 22.6 | 25.3 | 28.6 | 29.7 | 30.3 | 30.9 | 31.0 |
| 50–60 y (%) | 16.4 | 16.7 | 18.5 | 20.8 | 29.0 | 32.2 | 33.2 |
| Female (%) | 52.0 | 52.0 | 51.0 | 51.2 | 52.2 | 52.5 | 52.0 |
| Rural areas (%) | 67.9 | 71.8 | 71.0 | 71.4 | 71.7 | 71.8 | 70.7 |
| Less than high school education (%) | 82.5 | 81.4 | 78.8 | 75.1 | 73.3 | 70.5 | 71.7 |
| Adjusted household income4 | 12.0 ± 8.8 | 13.8 ± 11.9 | 16.2 ± 13.3 | 20.0 ± 20.1 | 24.2 ± 24.4 | 28.5 ± 36.8 | 39.9 ± 46.6 |
| Smoker (%) | 32.4 | 31.3 | 33.4 | 29.2 | 32.2 | 31.2 | 31.5 |
| Men | 64.0 | 61.6 | 64.4 | 56.4 | 64.3 | 63.1 | 62.7 |
| Women | 3.3 | 3.4 | 3.5 | 3.2 | 2.9 | 2.4 | 2.6 |
| Alcohol drinker (%) | 35.5 | 33.6 | 37.9 | 32.6 | 34.2 | 33.8 | 36.3 |
| Men | 60.6 | 58.0 | 66.5 | 57.4 | 62.2 | 62.7 | 65.0 |
| Women | 12.3 | 11.1 | 10.3 | 8.8 | 8.7 | 7.7 | 9.7 |
| Weight (kg) | 55.8 ± 9.0 | 56.2 ± 9.0 | 57.8 ± 9.8 | 59.7 ± 10.3 | 60.5 ± 10.6 | 61.1 ± 10.7 | 61.8 ± 11.0 |
| Men | 59.2 ± 8.6 | 59.9 ± 8.5 | 61.5 ± 8.6 | 63.8 ± 10.2 | 64.8 ± 10.5 | 65.6 ± 10.6 | 66.5 ± 11.0 |
| Women | 52.7 ± 8.2 | 53.0 ± 8.2 | 54.4 ± 9.8 | 56.1 ± 8.9 | 56.7 ± 9.1 | 57.0 ± 8.9 | 57.6 ± 9.2 |
| BMI (kg/m2) | 21.7 ± 2.8 | 21.9 ± 2.7 | 22.3 ± 3.0 | 22.9 ± 3.1 | 23.1 ± 3.2 | 23.3 ± 3.2 | 23.4 ± 3.4 |
| Men | 21.5 ± 2.5 | 21.7 ± 2.5 | 22.2 ± 2.8 | 22.8 ± 3.0 | 23.1 ± 3.1 | 23.3 ± 3.1 | 23.5 ± 3.3 |
| Women | 22.0 ± 2.9 | 22.0 ± 2.9 | 22.5 ± 3.1 | 23.0 ± 3.2 | 23.2 ± 3.3 | 23.2 ± 3.3 | 23.3 ± 3.4 |
| SBP (mm Hg) | 112.2 ± 15.6 | 112.7 ± 14.9 | 116.1 ± 15.6 | 116.9 ± 15.5 | 119.1 ± 16.0 | 118.6 ± 15.7 | 120.8 ± 16.6 |
| Men | 114.7 ± 14.8 | 115.0 ± 13.7 | 118.2 ± 14.3 | 119.2 ± 14.2 | 121.5 ± 14.9 | 121.0 ± 14.6 | 122.9 ± 15.1 |
| Women | 109.9 ± 15.9 | 110.7 ± 15.6 | 114.1 ± 16.5 | 114.8 ± 16.2 | 116.9 ± 16.7 | 116.5 ± 16.2 | 118.8 ± 17.6 |
| DBP (mm Hg) | 73.5 ± 10.7 | 74.6 ± 10.3 | 76.2 ± 10.4 | 76.9 ± 10.5 | 78.1 ± 10.9 | 78.3 ± 10.5 | 79.8 ± 11.0 |
| Men | 75.2 ± 10.5 | 76.2 ± 10.0 | 77.8 ± 10.2 | 78.7 ± 10.1 | 79.9 ± 10.5 | 80.3 ± 10.3 | 81.8 ± 10.6 |
| Women | 72.0 ± 10.8 | 73.2 ± 10.4 | 74.8 ± 10.5 | 75.3 ± 10.7 | 76.5 ± 10.9 | 76.4 ± 10.4 | 78.0 ± 11.0 |
Age, weight, BMI, SBP, and DBP were significantly greater in 2009 than in any earlier year (P-trend < 0.01, general linear regression models). Percentage of participants aged ≥50 y who lived in urban areas and who achieved higher education were greater in 2009 than in earlier years (P-trend < 0.01, chi-square tests). Percentage of females, alcohol drinkers, and smokers did not significantly change over time (P-trend > 0.05, chi-square tests). DBP, diastolic blood pressure; SBP, systolic blood pressure.
The percentage of participants who participated previously is different from the follow-up rate, because participants younger than 20 y or older than 60 y were excluded from the analysis.
Mean ± SD (all such values).
Adjusted to Chinese yuan value in 2009 (per 1000 yuan).