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Table 1 Baseline characteristics of participants according to the quartiles of glycemic index (GI) and carbohydrate intake

From: Dietary carbohydrate quality and risk of breast cancer among women

  Case (n = 461) Control (n = 495) p-value a Quartile of glycemic index)units/d) p-valueb
1 2 3 4
No of case/controls     110/129 106/133 122/117 123/116  
Age, year 46.0 ± 10.31 44.05 ± 11.26 0.0003 46.7 ± 10.7 45.9 ± 10.7 43.1 ± 10.8 44.1 ± 10.7 < 0.001
BMI (kg/m2) 28.07 ± 5.20 28.87 ± 6.05 0.01 28.3 ± 4.9 29.0 ± 6.0 28.1 ± 5.9 28.4 ± 5.6 0.47
Physical activity (MET-h/week) 23.09 ± 4.80 29.37 ± 44.19 0.01 34.1 ± 54.3 33.8 ± 51.6 20.5 ± 30.8 16.8 ± 22.2 < 0.001
Age at menarche (years) 13.02 ± 2.54 12.92 ± 2.76 0.28 12.9 ± 2.6 13.1 ± 2.4 12.7 ± 2.7 13.0 ± 2.7 0.50
Age at first birth (years) 18.89 ± 8.51 17.3 ± 8.27 0.002 18.5 ± 8.42 17.8 ± 8.1 17.8 ± 8.6 18.0 ± 8.5 0.78
Menopausal status (%)
 Premenopausal 301(66.59) 325 (67.15) 0.85 133 (56.6) 157 (66.8) 170 (72.9) 165 (70.5) 0.01
 Postmenopausal 151(33.41) 159 (32.85)   102 (43.4) 78 (33.1) 63 (27.0) 69 (29.4)  
Educational level (%)
 Un university 379 (83.85) 406 (84.06) 0.93 191 (81.6) 203 (8.3) 190 (81.9) 201 (85.9) 0.34
 University 73 (16.15) 77 (15.94)   43 (18.3) 32 (13.6) 42 (18.1) 33 (14.1)  
Marital status (%)
 Married 369 (81.6) 415 (87.0) 0.05 195 (83.6) 197 (84.9) 196 (84.8) 196 (84.1) 0.97
 Unmarried/divorced/widowed 83 (18.3) 62 (13.0)   38 (16.3) 35 (15.0) 35 (15.1) 37 (15.8)  
Family history of breast cancer (%) 44 (9.73) 7 (1.42) 0.000 13 (5.4) 12 (5.0) 13 (5.5) 13 (5.4) 0.99
Oral contraceptive use (%) 236 (53.03) 258 (61.43) 0.01 117 (53.9) 135 (62.7) 116 (54.9) 126 (56.7) 0.24
Current smoker (%) 16 (3.54) 24 (4.98) 0.27 14 (5.9) 5 (2.1) 8 (3.4) 13 (5.5) 0.12
Alcohol use (%) 12 (2.65) 29 (6.00) 0.01 15 (6.3) 7 (2.9) 14 (6.0) 5 (2.1) 0.05
Postmenopausal hormone use (%) 2 (0.43) 10 (2.02) 0.02 3 (1.2) 4 (1.6) 1 (0.4) 4 (1.6) 0.56
Parity
 Nulliparous/missing 210 (42.42) 204 (44.25) 0.75 109 (45.6) 97 (40.5) 109 (45.6) 99 (41.4) 0.33
 1 51(10.30) 39 (8.46)   27 (11.3) 15 (6.2) 22 (9.2) 26 (10.8)  
 2–3 154 (31.11) 147 (31.89)   69 (28.8) 79 (33.0) 72 (30.1) 81 (33.8)  
  ≥ 4 80 (16.16) 71 (15.40)   34 (14.2) 48 (20.0) 36 (15.0) 33 (13.8)  
  1. aχ2 Test for ordinal qualitative variables and t-test for continuous variable
  2. bP-values were determined by the ANOVA test