Table 2.
Clinical characteristics, dietary nutrients intake data, and socioeconomical status factors of the study subjects according to different household income groups.
| Total subjects (n = 2,266) | Group 1 (n = 76) | Group 2 (n = 472) | Group 3 (n = 1,049) | Group 4 (n = 403) | Group 5 (n = 239) | Group 6 (n = 26) | P for trend adjusted for age and sex | |
|---|---|---|---|---|---|---|---|---|
| Age (year) | 43.4 ± 9.8 | 34.5 ± 13.5 | 36.6 ± 11.0 | 44.0 ± 7.7 | 48.6 ± 7.3 | 48.4 ± 7.7 | 48.9 ± 7.7 | <0.001 ** |
| Proportion of women (%) | 10.6 | 31.6 | 13.8 | 7.0 | 7.7 | 18.0 | 15.4 | <0.001 ** |
| Clinical characteristics | ||||||||
| Body mass index (kg/m2) | 23.1 ± 3.3 | 21.8 ± 3.5 | 22.7 ± 3.4 | 23.3 ± 3.3 | 23.1 ± 3.0 | 23.3 ± 2.9 | 24.6 ± 3.6 | 0.049 * |
| Systolic blood pressure (mmHg) | 123.4 ± 16.1 | 124.0 ± 20.4 | 122.1 ± 15.7 | 123.6 ± 16.1 | 124.2 ± 16.1 | 123.4 ± 15.8 | 127.2 ± 17.3 | 0.013 * |
| Diastolic blood pressure (mmHg) | 77.1 ± 12.0 | 73.0 ± 12.4 | 74.3 ± 11.6 | 77.8 ± 11.9 | 78.4 ± 11.5 | 77.6 ± 12.6 | 79.3 ± 13.7 | 0.547 |
| Serum total cholesterol (mg/dL) | 200.0 ± 35.1 | 186.4 ± 26.1 | 193.3 ± 36.0 | 200.9 ± 36.5 | 202.4 ± 31.5 | 201.9 ± 33.0 | 199.6 ± 34.5 | 0.132 |
| Serum triglyceride (mg/dL) | 125.8 ± 180.0 | 100.0 ± 51.3 | 116.3 ± 85.6 | 130.2 ± 230.1 | 123.5 ± 94.1 | 120.5 ± 130.5 | 166.0 ± 149.3 | 0.866 |
| Serum HDL cholesterol (mg/dL) | 61.8 ± 16.5 | 60.4 ± 13.3 | 62.3 ± 16.3 | 61.6 ± 16.7 | 61.3 ± 16.3 | 63.6 ± 16.7 | 58.7 ± 16.4 | 0.931 |
| Fasting plasma glucose (mg/dL) | 95.0 ± 23.2 | 89.5 ± 23.4 | 92.2 ± 21.8 | 95.2 ± 23.6 | 97.1 ± 22.2 | 93.7 ± 20.2 | 103.2 ± 45.8 | 0.954 |
| SES factors | ||||||||
| Years of education (year) | 14.5 ± 2.5 | 14.1 ± 2.9 | 14.6 ± 2.7 | 14.3 ± 2.6 | 14.8 ± 2.3 | 15.2 ± 2.0 | 15.6 ± 3.5 | <0.001 ** |
| Managerial Position (%) | 22.7 | 0 | 2.5 | 13.1 | 50.9 | 60.3 | 65.4 | <0.001 ** |
| Annual household income (ten thousands yen/year) | 443.0 ± 188.5 | 127.5 ± 29.3 | 312.2 ± 87.1 | 415.6 ± 123.2 | 522.5 ± 129.3 | 720.5 ± 151.5 | 1078.3 ± 167.6 | <0.001 ** |
| Dietary intake levels | ||||||||
| Total energy intake (kJ/day) | 7,705.8 ± 2,396.0 | 7,424.5 ± 2,763.3 | 7,496.8 ± 2,461.2 | 7,780.5 ± 2,427.8 | 7,827.8 ± 2,209.2 | 7,717.7 ± 2,310.5 | 7,389.8 ± 2,196.8 | 0.022 * |
| Total energy adjusted salt intake (g/1,000 kJ·day) | 1.39 ± 0.31 | 1.43 ± 0.35 | 1.40 ± 0.31 | 1.39 ± 0.32 | 1.38 ± 0.29 | 1.37 ± 0.26 | 1.34 ± 0.36 | <0.001 ** |
Values are shown as mean ± standard deviation or percentage. Subjects are classified into 6 grades according to their self-reported household incomes (1, <3.0 million yen/year; 2, 3.0–4.99 million yen/year; 3, 5.0–7.99 million yen/year; 4, 8.0–9.99 million yen/year; 5, 10.0–15.0 million yen/year; 6, >15.0 million yen/year) and are compared among different grades. The income data for one person is missing. For continuous variables we used linear regression analysis adjusted for age and sex. For categorized variables, we used logistic regression analysis adjusted for age and sex. * P < 0.05, ** P < 0.01.