Table 1.
Baseline characteristics of the study population by age at menarche category: the CARDIA Study
| Age at Menarche (years) | ||||
| 8–11 | 12–13 | 14–17 | ||
| African-American (n=1,333) | Mean (SD) or n (%) | Mean (SD) or n (%) | Mean (SD) or n (%) | p-trend |
| n (%) | 294 (22.1) | 749 (56.2) | 290 (21.8) | |
| Age at menarche (years) | 10.5 (0.8) | 12.5 (0.5) | 14.7 (0.8) | |
| Age at baseline (years) | 24.3 (3.8) | 24.6 (3.8) | 23.9 (4.0) | 0.35 |
| BMI (kg/m2) | 27.6 (6.6) | 25.8 (6.4) | 24.0 (5.7) | <.0001 |
| Waist circumference (cm) | 79.4 (13.7) | 76.4 (13.1) | 73.5 (11.7) | <.0001 |
| Height (cm) | 163.0 (7.0) | 163.8 (6.5) | 163.8 (7.3) | 0.14 |
| Physical activity at baseline (MET h/week) | 283.4 (206.5) | 270.3 (234.2) | 294.1 (231.5) | 0.60 |
| Physical activity prior to high school (activity index) | 3.5 (1.2) | 3.7 (1.2) | 3.9 (1.2) | 0.0005 |
| Physical activity during high school (activity index) | 3.7 (1.2) | 3.9 (1.1) | 3.9 (1.1) | 0.01 |
| Smoking status | 0.97 | |||
| Never | 177 (60.2) | 461 (61.6) | 173 (59.9) | |
| Former | 25 (8.5) | 67 (9.0) | 26 (9.0) | |
| Current | 92 (31.3) | 221 (29.5) | 90 (31.1) | |
| Alcohol (g/day) | 5.1 (11.1) | 4.9 (10.7) | 6.5 (16.5) | 0.15 |
| Ever used oral contraceptives (yes) | 240 (82.0) | 590 (78.8) | 225 (77.6) | 0.20 |
| Education | 0.21 | |||
| <High school | 27 (9.2) | 70 (9.3) | 28 (9.7) | |
| High school | 200 (68.0) | 537 (71.6) | 209 (72.1) | |
| >High school | 67 (22.8) | 143 (19.1) | 53 (18.2) | |
| Parental history of diabetes (yes) | 83 (28.1) | 186 (24.7) | 63 (21.7) | 0.07 |
| Impaired fasting glucose (yes) | 4 (1.4) | 16 (2.1) | 3 (1.0) | 0.77 |
| Glucose (mg/dl) | 80.3 (7.5) | 79.3 (8.5) | 79.0 (8.0) | 0.05 |
| Insulin (uU/ml) | 14.6 (7.6) | 13.0 (6.3) | 12.8 (5.5) | 0.004 |
| LDL-C (mg/dl) | 110.0 (31.8) | 110.9 (31.5) | 110.4 (33.0) | 0.87 |
| HDL-C (mg/dl) | 54.8 (13.4) | 55.4 (12.7) | 55.7 (13.0) | 0.33 |
| Triglycerides (mg/dl) | 62.8 (30.5) | 63.1 (30.8) | 63.2 (37.6) | 0.92 |
| Total cholesterol (md/dl) | 177.3 (34.7) | 178.9 (33.3) | 178.7 (34.8) | 0.58 |
| Systolic blood pressure (mmHg) | 109.0 (10.3) | 108.4 (10.1) | 106.6 (9,1) | 0.003 |
| Diastolic blood pressure (mmHg) | 68.2 (9.6) | 67.5 (9,3) | 66.6 (9.4) | 0.03 |
| Age at Menarche (years) | ||||
| 8–11 | 12–13 | 14–17 | ||
| White (n=1,250) | Mean (SD) or n (%) | Mean (SD) or n (%) | Mean (SD) or n (%) | p-trend |
| n (%) | 213 (17.0) | 736 (58.9) | 301 (24.1) | |
| Age at menarche (years) | 10.6 (0.7) | 12.5 (0.5) | 14.7 (0.9) | |
| Age at baseline (years) | 25.4 (3.6) | 25.5 (3.4) | 25.4 (3.3) | 0.99 |
| BMI (kg/m2) | 24.4 (5.4) | 23.1 (4.3) | 22.0 (3.3) | <.0001 |
| Waist circumference (cm) | 73.8 (11.1) | 71.9 (9.1) | 70.0 (7.4) | <.0001 |
| Height (cm) | 164.0 (6.2) | 165.4 (6.4) | 165.4 (6.5) | 0.02 |
| Physical activity (MET-h/week) | 385.9 (237.9) | 395.8 (261.8) | 417.9 (271.2) | 0.15 |
| Physical activity prior to high school | 3.5 (1.1) | 3.6 (1.1) | 3.7 (1.1) | 0.19 |
| Physical activity in high school | 3.5 (1.1) | 3.6 (1.1) | 3.8 (1.0) | 0.0001 |
| Current smoker | 0.35 | |||
| Never | 126 (59.2) | 378 (51.4) | 162 (53.8) | |
| Former | 37 (17.5) | 160 (21.7) | 55 (18.3) | |
| Current | 50 (23.5) | 198 (26.9) | 84 (27.9) | |
| Alcohol (g/day) | 6.7 (12.3) | 10.2 (4.6) | 10.5 (17.1) | 0.01 |
| Ever used oral contraceptives | 158 (74.2) | 560 (75.6) | 218 (72.4) | 0.55 |
| Education | 0.90 | |||
| <High school | 10 (4.7) | 27 (3.7) | 14 (4.7) | |
| High school | 112 (52.2) | 344 (46.7) | 152 (50.5) | |
| >High school | 91 (43.0) | 365 (49.6) | 135 (44.9) | |
| Parental history of diabetes (yes) | 38 (17.8) | 112 (15.1) | 35 (11.6) | 0.05 |
| Impaired fasting glucose (yes) | 6 (2.8) | 10 (1.4) | 3 (1.0) | 0.12 |
| Glucose (mg/dl) | 81.4 (8.1) | 80.6 (7.4) | 80.2 (7.0) | 0.08 |
| Insulin (uU/ml) | 11.1 (5.6) | 10.2 (4.6) | 10.1 (4.6) | 0.04 |
| LDL-C (mg/dl) | 106.0 (29.7) | 106.6 (29.2) | 104.0 (27.7) | 0.41 |
| HDL-C (mg/dl) | 55.0 (13.4) | 55.7 (12.8) | 58.3 (13.1) | 0.002 |
| Triglycerides (mg/dl) | 71.9 (36.0) | 69.2 (39.4) | 67.4 (35.4) | 0.19 |
| Total cholesterol (md/dl) | 175.3 (31.2) | 176.1 (31.3) | 175.8 (30.4) | 0.84 |
| Systolic blood pressure (mmHg) | 105.1 (9.3) | 105.1 (9.4) | 104.2 (9,2) | 0.24 0.26 |
| Diastolic blood pressure (mmHg) | 66.9 (8.1) | 66.1 (8.7) | 65.9 (8.2) | 0.26 |