Skip to main content

Table 1 Characteristics of participants with complete data at both 18th and 22th-year follow-ups compared with those participants with missing data, loss of follow-up or death, stratified by sex

From: Associations between body mass index, body composition and bone density in young adults: findings from a southern Brazilian cohort

Variables Men   Women  
Mean or median (SD or p25-p75); %   Mean or median (SD or p25-p75); %  
Participants included Participants excluded1 p-value Participants included Participants excluded1 p-value
N = 1408 N = 1195 N = 1560 N = 1085
Perinatal
Maternal education (years) N = 1406 N = 1193 0.183a N = 1557 N = 1085 0.003a
 0–4 25.3 29.2 26.7 32.0
 5–8 47.6 45.3 46.4 45.2
 9–11 18.6 17.5 19.0 14.5
 ≥12 8.5 8.0 7.9 8.3
Family income (MMW) N = 1388 N = 1159 0.039a N = 1528 N = 970 0.272a
 ≤1 17.9 20.6 17.3 20.3
 1.1–3 42.4 42.3 41.6 40.6
 3.1–6 24.4 20.2 24.9 23.5
 >6 15.3 16.9 16.2 15.6
Gestational age (weeks) N = 1391 N = 1159 0.321a N = 1539 N = 1050 0.002a
 <34 1.2 2.0 1.2 2.9
 34–36 6.2 6.4 7.8 6.7
 37–40 75.8 76.1 77.2 79.3
 >40 16.8 15.5 13.8 11.1
Maternal nutritional status (BMI) N = 1366 N = 1155 0.182a N = 1530 N = 1046 0.237a
 Low weight 10.4 9.1 8.0 7.8
 Adequate 67.3 69.7 67.6 71.3
 Overweight 17.9 15.7 19.4 16.5
 Obese 4.4 5.5 5.0 4.4
Birth weight (grams) N = 1407 N = 1188 0.017a N = 1559 N = 1078 < 0.001a
 <2500 7.5 10.1 10.9 10.6
 2500–2999 22.5 19.2 26.1 33.4
 3000–3999 64.0 63.3 59.2 53.6
 ≥4000 6.0 7.4 3.8 2.4
Length at birth (centimeters) N = 1395 N = 1165 0.901b N = 1548 N = 1054 0.029b
49.1 (2.3) 49.1 (2.6) 48.5 (2.3) 48.3 (2.3)
15 years
Skin color N = 1345 N = 765 0.108a N = 1540 N = 673 0.597a
 White 63.0 66.5 63.4 64.6
 Black, brown or other 37.0 33.5 36.6 35.4
18 years
Smoking habit N = 1408 N = 606 0.015a N = 1560 N = 531 0.005a
 No 86.0 81.7 88.2 83.2
 Yes 14.0 18.3 11.8 16.8
Total physical activity (min/week) N = 1406 N = 602 0.203c N = 1559 N = 528 0.966c
630.0 (300.0 1110.0) 592.5 (260.0; 1140.0) 270.0 (110.0; 600.0) 280.0 (120.0; 600.0)
Total calcium consumption (mg) N = 1406 N = 587 0.282c N = 1559 N = 517 0.656c
674.8 (488.9; 939.4) 670.6 (479.5; 897.8) 638.1 (449.3; 922.1) 660.2 (477.4; 891.4)
Lean mass index (kg/m2) N = 1408 N = 493 0.281b N = 1560 N = 390 0.002b
18.0 (1.5) 18.0 (1.7) 14.0 (1.4) 14.3 (1.6)
Fat mass index (kg/m2) N = 1408 N = 493 0.012b N = 1560 N = 390 < 0.001b
4.1 (2.9) 4.5 (3.5) 8.3 (3.5) 9.0 (3.9)
Body mass index (kg/m2) N = 1408 N = 570 < 0.001b N = 1560 N = 449 < 0.001b
23.0 (3.6) 24.2 (5.5) 23.2 (4.4) 24.6 (5.8)
22 years
 Lean mass index (kg/m2) N = 1408 N = 133 0.185b N = 1560 N = 217 < 0.001b
18.2 (1.7) 18.0 (2.0) 14.3 (1.7) 14.8 (1.9)
 Fat mass index (kg/m2) N = 1408 N = 133 0.571b N = 1560 N = 217 < 0.001b
5.5 (3.4) 5.7 (4.0) 9.8 (4.1) 11.0 (5.0)
 Body mass index (kg/m2) N = 1408 N = 279 < 0.001b N = 1560 N = 315 < 0.001b
24.7 (4.2) 26.2 (6.7) 25.1 (5.3) 27.3 (7.3)
 Whole body BMD (g/cm2) N = 1408 N = 139 0.041b N = 1560 N = 221 0.532b
1.3 (0.1) 1.2 (0.1) 1.2 (0.1) 1.2 (0.1)
 Lumbar spine BMD (g/cm2) N = 1408 N = 164 0.542b N = 1560 N = 220 0.886b
1.2 (0.1) 1.2 (0.2) 1.2 (0.1) 1.2 (0.1)
 Femoral neck BMD (g/cm2) N = 1408 N = 164 0.187b N = 1560 N = 220 0.355b
1.2 (0.2) 1.2 (0.2) 1.0 (0.1) 1.0 (0.1)
Outcome changes (Δ) at 18–22 years*
 Whole body BMD change (g/cm2) N = 1408 N = 12 0.174c N = 1560 N = 10 0.241c
0.04 (0.02; 0.07) 0.04 (0.01; 0.05) 0.02 (0.01; 0.04) 0.04 (0.02; 0.06)
 Lumbar spine BMD change (g/cm2) N = 1406 N = 62 0.514c N = 1558 N = 32 0.980c
0.06 (0.02; 0.10) 0.05 (0.01; 0.09) 0.04 (0.01; 0.07) 0.04 (0.01; 0.07)
 Femoral neck BMD change (g/cm2) N = 1407 N = 59 0.486c N = 1547 N = 43 0.412c
0.01 (−0.05; 0.06) 0.02 (−0.04; 0.07) 0.01 (−0.03; 0.05) 0.02 (−0.02; 0.10)
  1. N Number of observations, SD standard deviation, % percentage, MMW monthly minimum wages, BMI body mass index, BMD bone mineral density (g/m2)
  2. *Changes in measurement of BMD at 22y – at 18y
  3. 1Participants excluded from the analyses due to loss of follow-up or missing data;
  4. aP value refers to Chi-squared heterogeneity test;
  5. bP value refers to Student’s t-test;
  6. cP value refers to Wilcoxon Rank Sum Test
  7. The 1993 Pelotas Birth Cohort, Brazil