Table 1.
Characteristics of study participants by country: INTERMAP, 1996–1999
| Japan | PRC | UK | US | P valuea | |||||
|---|---|---|---|---|---|---|---|---|---|
| Total (n) | 1145 | 839 | 497 | 2195 | |||||
| Men (n) | 574 | (50.1) | 416 | (49.6) | 264 | (53.1) | 1103 | (50.3) | 0.627 |
| Age (years) | 49.4 | (5.3) | 49.0 | (5.8) | 49.2 | (5.6) | 49.1 | (5.4) | 0.423 |
| Body mass index (kg/sq.m) | 23.4 | (2.9) | 23.1 | (3.4) | 27.5 | (4.6) | 28.9 | (5.9) | <0.001 |
| Pulse rate | |||||||||
| Mean of 4 visits (beats/min) | 71.4 | (8.8) | 73.9 | (8.4) | 71.3 | (9.4) | 73.3 | (9.4) | <0.001 |
| 1st visit (beats/min) | 71.4 | (10.1) | 74.2 | (9.9) | 70.0 | (10.4) | 72.6 | (10.6) | <0.001 |
| 2nd visit (beats/min) | 71.5 | (9.8) | 73.6 | (9.8) | 71.5 | (10.5) | 73.8 | (11.0) | <0.001 |
| 3rd visit (beats/min) | 71.2 | (10.1) | 74.0 | (9.9) | 71.5 | (10.8) | 73.0 | (10.6) | <0.001 |
| 4th visit (beats/min) | 71.4 | (10.0) | 73.9 | (9.9) | 72.2 | (10.4) | 73.9 | (10.4) | <0.001 |
| Systolic blood pressure | |||||||||
| Mean of 4 visits (mmHg) | 117.2 | (13.8) | 121.3 | (17.4) | 120.4 | (14.6) | 118.6 | (13.9) | <0.001 |
| 1st visit (mmHg) | 119.5 | (15.5) | 124.7 | (20.3) | 123.8 | (16.6) | 120.7 | (15.8) | <0.001 |
| 2nd visit (mmHg) | 116.6 | (14.6) | 120.2 | (18.1) | 119.2 | (15.3) | 118.2 | (14.7) | <0.001 |
| 3rd visit (mmHg) | 116.5 | (14.4) | 120.8 | (18.7) | 120.2 | (15.5) | 118.1 | (14.9) | <0.001 |
| 4th visit (mmHg) | 116.3 | (14.4) | 119.3 | (17.6) | 118.3 | (14.5) | 117.3 | (14.6) | <0.001 |
| VIM of average BP across four study visits | 5.44 | (2.88) | 6.85 | (3.49) | 5.65 | (2.81) | 5.84 | (3.01) | <0.001 |
| CV of average BP across four study visits | 6.58 | (3.53) | 7.07 | (3.54) | 6.64 | (3.41) | 6.50 | (3.82) | 0.002 |
| Diastolic blood pressure | |||||||||
| Mean of 4 visits (mmHg) | 73.6 | (10.3) | 73.2 | (10.2) | 77.2 | (9.9) | 73.4 | (9.7) | <0.001 |
| 1st visit (mmHg) | 74.7 | (11.4) | 74.3 | (11.8) | 78.8 | (11.1) | 74.4 | (10.9) | <0.001 |
| 2nd visit (mmHg) | 73.5 | (11.1) | 72.7 | (11.4) | 76.7 | (10.8) | 73.1 | (10.5) | <0.001 |
| 3rd visit (mmHg) | 73.1 | (11.0) | 73.1 | (11.0) | 77.1 | (10.4) | 73.1 | (10.5) | <0.001 |
| 4th visit (mmHg) | 73.4 | (11.0) | 72.6 | (10.9) | 76.3 | (10.7) | 73.0 | (10.4) | <0.001 |
| Urinary sodium (mmol/24 h) | 198.3 | (56.2) | 227.5 | (100.3) | 145.0 | (49.1) | 162.6 | (59.4) | <0.001 |
| Urinary potassium (mmol/24 h) | 48.9 | (13.6) | 38.3 | (12.7) | 68.2 | (20.1) | 57.7 | (20.9) | <0.001 |
| Drinking status | |||||||||
| Heavy drinker (n) | 236 | (20.6) | 78 | (9.3) | 63 | (12.6) | 98 | (4.5) | <0.001 |
| Moderate drinker (n) | 803 | (70.1) | 304 | (36.2) | 377 | (75.9) | 1435 | (65.4) | |
| Ex-drinker (n) | 26 | (2.3) | 41 | (4.9) | 24 | (4.8) | 427 | (19.5) | |
| Nondrinker (n) | 80 | (7.0) | 416 | (49.6) | 33 | (6.6) | 235 | (10.7) | |
| Smoking status | |||||||||
| Smoker (n) | 346 | (30.2) | 305 | (36.4) | 87 | (17.4) | 369 | (16.8) | <0.001 |
| Ex-smoker (n) | 157 | (13.7) | 69 | (8.2) | 146 | (29.4) | 677 | (30.8) | |
| Non-smoker (n) | 642 | (56.1) | 465 | (55.4) | 264 | (53.1) | 1149 | (52.3) | |
| Mean inside temperature (°C) | 22.5 | (3.3) | 16.3 | (3.4) | 21.4 | (1.9) | 23.1 | (1.1) | <0.001 |
| Mean outside temperature (°C) | 14.5 | (6.9) | 12.3 | (5.0) | 8.6 | (4.5) | 18.8 | (9.9) | <0.001 |
| Physical activity (hours/week)a | 2.6 | (3.6) | 6.0 | (3.8) | 2.2 | (2.4) | 3.2 | (3.2) | <0.001 |
| Year of education | |||||||||
| 6 years or less | 0 | (0.0) | 580 | (69.1) | 6 | (1.2) | 17 | (0.8) | <0.001 |
| 12 years or less | 894 | (78.1) | 257 | (30.6) | 267 | (53.7) | 522 | (23.8) | |
| More than 13 year | 251 | (21.9) | 2 | (0.2) | 224 | (45.1) | 1656 | (75.4) | |
| Past history of CVD (n) | 98 | (8.6) | 45 | (5.4) | 45 | (9.1) | 193 | (8.8) | 0.013 |
| Family history of HBP (n) | 528 | (46.1) | 298 | (35.5) | 241 | (48.5) | 1491 | (67.9) | <0.001 |
| Anti-hypertension drug class | |||||||||
| ACE inhibitor (n) | 20 | (1.7) | 11 | (1.3) | 26 | (5.2) | 196 | (8.9) | <0.001 |
| Angiotensin II receptor blocker (n) | 0 | (0.0) | 0 | (0.0) | 5 | (1.0) | 18 | (0.8) | 0.001 |
| Beta blocker (n) | 13 | (1.1) | 4 | (0.5) | 24 | (4.8) | 116 | (5.3) | <0.001 |
| Calcium channel blocker (n) | 50 | (4.4) | 23 | (2.7) | 16 | (3.2) | 137 | (6.2) | <0.001 |
| Diuretic (n) | 5 | (0.4) | 19 | (2.3) | 19 | (3.8) | 160 | (7.3) | <0.001 |
| Direct vasodilators (n) | 5 | (0.4) | 14 | (1.7) | 0 | (0.0) | 9 | (0.4) | <0.001 |
| Other (n) | 5 | (0.4) | 3 | (0.4) | 2 | (0.4) | 27 | (1.2) | 0.017 |
Values are number (proportion [%]) or mean (standard deviation)
a
Analysis of variance for continuous variables or chi-square tests for proportions. Physical activity was defined as number of hours with moderate and heavy physical activity per week
BP blood pressure, VIM variation independent of mean, CV coefficient of variation, CVD cardiovascular disease, HBP high blood pressure, PRC People’s Republic of China, UK United Kingdom, US United States