Table 1.
Characteristics of the Participants Used to Assess Associations of Body Weight and Composition Trajectories with Lung Function at 15 Years
| Total (n = 3,575) | Boys (n = 1,687) | Girls (n = 1,888) | P Value | |
|---|---|---|---|---|
| Potential confounders | ||||
| Maternal social class | 2,941 | |||
| Professional and intermediate | 1,322 | 639 (46.2) | 683 (43.8) | 0.712 |
| Skilled nonmanual | 1,179 | 554 (40.1) | 625 (40.1) | |
| Skilled manual, partly skilled, and unskilled | 440 | 190 (13.7) | 250 (16.1) | |
| Maternal smoking during pregnancy | 3,278 | 260 (16.8) | 290 (16.7) | 0.930 |
| Birth weight, g | 3,381 | 3,485 (3,160 to 3,860) | 3,402 (3,120 to 3,700) | <0.0001 |
| Birth weight, z-score* | 3,366 | 0.5 (1.1) | 0.5 (1.0) | 0.686 |
| Gestation, wk | 3,425 | 40 (39 to 41) | 40 (39 to 41) | <0.0001 |
| Ever breastfed | 3,335 | 1,385 (88.1) | 1,521 (86.3) | 0.137 |
| Total energy intake at 7 yr, kcal | 3,004 | 1,758 (1,586 to 1,973) | 1,630 (1,457 to 1,819) | <0.0001 |
| Wear-time in MVPA at 11 yr, min | 2,955 | 24.4 (15.4 to 36.5) | 15.6 (9.4 to 24.7) | <0.0001 |
| Smoking at 14 yr | 2,790 | 42 (3.4) | 109 (7.0) | <0.0001 |
| Age at 15 yr, yr | 3,575 | 15.3 (15.3 to 15.5) | 15.3 (15.3 to 15.5) | 0.015 |
| Height at 15 yr, cm | 3,538 | 174.4 (169.4 to 179.2) | 164.4 (160.6 to 168.6) | <0.0001 |
| Height at 15 yr, z-score† | 3,538 | 0.4 (1.0) | 0.4 (0.9) | 0.017 |
| Lifetime doctor-diagnosed asthma | 3,573 | 443 (26.3) | 422 (22.4) | 0.006 |
| Pubertal status | ||||
| Age at menarche, yr | 1,701 | — | 12.7 (11.8 to 13.6) | — |
| Voice break status at age 15 yr | 1,649 | |||
| Not yet started | 218 | 218 (13.2) | — | — |
| Starting to break | 505 | 505 (30.6) | — | — |
| Completely broken | 926 | 926 (56.2) | — | — |
| Lung function measures (raw data) | ||||
| 8 yr (prebronchodilation) | ||||
| FVC, L | 3,078 | 2.0 (0.3) | 1.8 (0.3) | <0.0001 |
| FEV1, L | 3,045 | 1.7 (0.3) | 1.6 (0.3) | <0.0001 |
| FEF25–75, L/s | 3,078 | 2.0 (0.5) | 2.1 (0.5) | 0.017 |
| FEV1/FVC, % | 3,045 | 87.3 (6.8) | 89.4 (6.0) | <0.0001 |
| 15 yr (post-bronchodilation) | ||||
| FVC, L | 3,567 | 4.2 (0.9) | 3.3 (0.6) | <0.0001 |
| FEV1, L | 3,433 | 3.8 (0.8) | 3.1 (0.6) | <0.0001 |
| FEF25–75, L/s | 3,575 | 4.7 (1.2) | 4.0 (1.0) | <0.0001 |
| FEV1/FVC, % | 3,433 | 91.1 (6.6) | 93.0 (6.3) | <0.0001 |
| Lung function measures, z-scores‡ | ||||
| 8 yr (prebronchodilation) | ||||
| FVC, L | 2,807 | −0.04 (1.1) | −0.03 (1.0) | 0.853 |
| FEV1, L | 2,775 | −0.03 (1.0) | 0.02 (1.0) | 0.173 |
| FEF25–75, L/s | 2,807 | −0.11 (1.1) | −0.13 (1.0) | 0.736 |
| FEV1/FVC, % | 2,775 | 0.03 (1.1) | 0.07 (1.0) | 0.322 |
| 15 yr (post-bronchodilation) | ||||
| FVC, L | 3,245 | −0.87 (1.3) | −0.97 (1.3) | 0.024 |
| FEV1, L | 3,123 | −0.34 (1.3) | −0.58 (1.3) | <0.0001 |
| FEF25–75, L/s | 3,253 | 0.16 (1.1) | 0.08 (1.2) | 0.033 |
| FEV1/FVC, % | 3,123 | 0.91 (1.1) | 0.76 (1.1) | 0.0002 |
| Prebronchodilation lung function growth rates from age 8 to 15 yr§ | ||||
| FVC, ml/yr | 3,073 | 325.5 (105.8) | 214.4 (72.7) | <0.0001 |
| FEV1, ml/yr | 3,013 | 293.8 (94.3) | 200.7 (66.4) | <0.0001 |
| FEF25–75, (ml/s) · yr | 3,070 | 327.4 (139.8) | 234.2 (115.4) | <0.0001 |
Definition of abbreviations: FEF25–75 = forced expiratory flow, midexpiratory phase; MVPA = moderate to vigorous physical activity.
Data are shown as mean (SD), median (25th–75th percentiles), or n (%). Em dashes indicate “not relevant.”
P values were determined by the chi-square test, Student’s t test, or Mann-Whitney test comparing distributions across sexes. Bold values indicate P < 0.05.
Derived using the International Fetal and New-born Growth Consortium for the 21st Century standards. Note that 15 children had missing values for birth weight z-score because they did not have information for gestational age, which should be included in the equation.
Derived using the World Health Organization Child Growth Standards.
Derived using the Global Lung Initiative equations.
Rate of lung function growth for each parameter was calculated as: (prebronchodilation lung function measure at 15 yr − prebronchodilation lung function measure at 8 yr)/time of follow-up in years.