Table 4.
Characteristics of Participating ALSPAC Study Adolescents
| Mean (SD) for continuously measured variables and prevalence (%) for categorical variables | |||||||
|---|---|---|---|---|---|---|---|
| n | All | n | Males | n | Females | p Value a | |
| Exposure measurements | |||||||
| Total hip BMD (g/cm2) | 4368 | 1.11 (0.15) | 1944 | 1.17 (0.15) | 2424 | 1.05 (0.12) | <0.001 |
| Total hip BMC (g) | 4368 | 38.4 (10.2) | 1944 | 46.4 (8.92) | 2424 | 32.0 (5.44) | <0.001 |
| Femoral neck BMD (g/cm2) | 4368 | 1.09 (0.14) | 1944 | 1.14 (0.15) | 2424 | 1.05 (0.12) | <0.001 |
| Trochanter BMD (g/cm2) | 4368 | 0.88 (0.14) | 1944 | 0.94 (0.14) | 2424 | 0.83 (0.12) | <0.001 |
| CSMI (cm4) | 4368 | 2.07 (0.83) | 1944 | 2.72 (0.75) | 2424 | 1.56 (0.45) | <0.001 |
| TB BMD minus head (g/cm2) | 4368 | 1.09 (0.10) | 1944 | 1.14 (0.10) | 2424 | 1.04 (0.08) | <0.001 |
| TB BMC minus head (g) | 4368 | 2280.3 (489.8) | 1944 | 2567.0 (463.5) | 2424 | 2050.3 (375.7) | <0.001 |
| TB area minus head (cm2) | 4368 | 2078.7 (281.8) | 1944 | 2228.2 (247.6) | 2424 | 1958.8 (248.3) | <0.001 |
| Outcome measurement | |||||||
| cIMT (mm) | 4368 | 0.48 (0.04) | 1944 | 0.48 (0.05) | 2424 | 0.47 (0.04) | <0.001 |
| Confounder variables | |||||||
| Age (years) | 4368 | 17.8 (0.38) | 1944 | 17.8 (0.37) | 2424 | 17.8 (0.39) | 0.273 |
| Height (cm) | 4368 | 171.3 (9.26) | 1944 | 178.7 (6.61) | 2424 | 165.3 (6.25) | <0.001 |
| Loge fat mass (kg) | 4368 | 2.74 (0.60) | 1944 | 2.42 (0.64) | 2424 | 2.99 (0.41) | <0.001 |
| Lean mass (kg) | 4368 | 45.7 (9.95) | 1944 | 55.1 (6.19) | 2424 | 38.1 (4.28) | <0.001 |
| Current smoker [n (%)] b | 2836 | 476 (16.8) | 1271 | 194 (15.3) | 1565 | 282 (18.0) | 0.051 |
| Frequency of alcohol consumption [n (%)] b | 2836 | <0.001 | |||||
| Never or ≤monthly | 787 (27.8) | 299 (23.5) | 488 (31.2) | ||||
| 2–3 times/month | 1335 (47.0) | 595 (46.8) | 740 (47.3) | ||||
| ≥2/week | 714 (25.2) | 377 (29.7) | 337 (21.5) | ||||
| Maternal social class [n (%)] b | 2836 | 0.055 | |||||
| I | 243 (8.6) | 117 (9.2) | 126 (8.1) | ||||
| II | 1047 (36.9) | 494 (38.9) | 553 (35.3) | ||||
| III (non‐manual) | 1114 (39.3) | 495 (39.0) | 619 (39.5) | ||||
| III (manual | 176 (6.2) | 73 (5.7) | 103 (6.6) | ||||
| IV/V | 256 (9.0) | 92 (7.2) | 164 (10.5) | ||||
| Other variables | |||||||
| BMI | 4362 | 22.8 (4.1) | 1942 | 22.8 (4.1) | 2420 | 23.0 (4.2) | 0.001 |
SD = standard deviation; cIMT = common carotid intima‐media thickness; TB = total body; CSMI = cross‐sectional moment of inertia (cm4); BMD = bone mineral density; BMC = bone mineral content.
a
Unpaired t test for continuous variables and chi‐square test for categorical variables to assess the null hypothesis of no difference between males and females.
b
Valid data available only in a subgroup, n = 2836.