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Table 1 Characteristics of participants with complete data compared with participants with missing data or losses of follow-up, stratified by gender

From: Body mass index at 11 years and bone mass at age 18: path analysis within the 1993 Pelotas (Brazil) birth cohort study

Variables Males Females
N Mean (SD); percentage N Mean (SD); percentage
Participants included in the analysis Participants excluded from the analysisa p-value Participants included in the analysis Participants excluded from the analysisa p-value
Follow-up at 11 years       
Family income N = 1601 N = 590   N = 1706 N = 555  
  1219.77 (2966.82) 1054.02 (2403.48) 0.224b 1062.79 (1597.87) 849.28 (1565.43) 0.006b
Maternal education (years) N = 1601 N = 572   N = 1706 N = 535  
 0-4 24.9% 29.6% 0.099c 22.6% 35.9% <0.001c
 5-8 42.5% 42.1%   43.5% 44.1%  
 9-11 22.4% 20.1%   23.5% 13.6%  
 ≥12 10.2% 8.2%   10.4% 6.4%  
Skin color N = 1601 N = 509   N = 1706 N = 507  
 White 65.5% 60.5% 0.040c 65.2% 59.2% 0.013c
 Non-white 34.5% 39.5%   34.8% 40.8%  
Total physical activity (minutes/week) N = 1601 N = 515   N = 1706 N = 465  
  514.80 (523.77) 559.49 (563.32) 0.098b 347.41 (405.32) 325.42 (367.51) 0.29b
Smoking N = 1601 N = 484   N = 1706 N = 487  
 No 97.6% 96.3% 0.129c 98.1% 96.7% 0.061c
 Yes 2.4% 3.7%   1.9% 3.3%  
BMI z scored N = 1601 N = 583   N = 1706 N = 551  
  0.46 (1.22) 0.52 (1.35) 0.349b 0.27 (1.23) 0.31 (1.20) 0.531b
Follow-up at 18 years       
Total physical activity (minutes/week) N = 1601 N = 407   N = 1706 N = 381  
  855.53 (914.26) 910.45 (913.21) 0.279b 455.94 (583.28) 460.20 (521.76) 0.895b
Smoking N = 1601 N = 414   N = 1706 N = 385  
 No 86.2% 79.5% 0.001c 88.5% 81.0% <0.001c
 Yes 13.8% 20.5%   11.5% 19.0%  
BMI z scored N = 1601 N = 372   N = 1706 N = 295  
  0.25 (1.15) 0.45 (1.39) 0.005b 0.44 (1.18) 0.47 (1.30) 0.753b
Fat mass (kg) N = 1601 N = 369   N = 1706 N = 297  
  12.46 (8.72) 14.40 (12.60) <0.001b 20.75 (8.90) 21.19 (11.60) 0.453b
Fat free mass (kg) N = 1601 N = 369   N = 1706 N = 297  
  57.74 (7.04) 58.67 (8.25) 0.026b 40.15 (4.99) 40.67 (5.41) 0.101b
Height (m) N = 1601 N = 369   N = 1706 N = 298  
  1.74 (0.07) 1.74 (0.08) 0.857b 1.61 (0.06) 1.61 (0.06) 0.874b
Calcium intake (mg/day) N = 1601 N = 336   N = 1706 N = 316  
  709.16 (332.71) 726.61 (340.34) 0.384b 694.27 (351.62) 679.39 (364.83) 0.492b
Bone mineral content (g) N = 1601 N = 302   N = 1706 N = 246  
  2963.12 (465.24) 2927.32 (441.61) 0.216b 2410.69 (396.08) 2411.90 (386.86) 0.964b
Bone mineral density (g/cm2) N = 1601 N = 302   N = 1706 N = 246  
  1.22 (0.10) 1.22 (0.09) 0.544b 1.13 (0.08) 1.13 (0.08) 0.902b
  1. The 1993 Pelotas Birth Cohort. Brazil.
  2. N - Number of observations; SD - Standard deviation; BMI - body mass index
  3. aParticipants excluded from analysis due to losses of follow-up or missing data.
  4. bt-test
  5. cChi-square test
  6. dAccording to the World Health Organization for children and teenagers from 5 to 19 years.