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Table 1 Distribution of selected characteristics for 394 study participants, E3N cohort

From: Plasma concentration of brominated flame retardants and postmenopausal breast cancer risk: a nested case-control study in the French E3N cohort

 AllControlCase
N(%) or Mean (STD)N(%) or Mean (STD)N(%) or Mean (STD)
All participants394 (100)197 (100)197 (100)
Menopausal status and age at menopause at baseline
 Pre-menopausal78 (19.8)39 (19.8)39 (19.8)
 Post-menopausal316 (80.2)158 (80.2)158 (80.2)
Menopausal status and age at menopause at case’s date of diagnosis
 Pre-menopausal3 (0.8)2 (1.0)1 (0.5)
 Post-menopausal192 (48.7)99 (50.3)93 (47.2)
Age (years) at baseline56.3 (6.2)56.3 (6.2)56.3 (6.2)
Age (years) at case’s date of diagnosis68.4 (6.2)68.4 (6.2)68.4 (6.2)
BMI (kg/m2) at baseline
  < 25279 (70.8)136 (69.0)136 (69.0)
  ≥ 25115 (29.2)61 (31.0)61 (31.0)
BMI (kg/m2) at case’s date of diagnosis
  < 25261 (66.2)127 (64.5)134 (68.0)
  ≥ 25133 (33.8)70 (35.5)63 (32.0)
Total plasma lipid content (ng/L)5.4 (0.8)5.4 (0.9)5.4 (0.8)
Smoking status at baseline
 Never192 (48.7)90 (45.7)102 (51.8)
 Ever202 (51.3)107 (54.3)95 (48.2)
Physical activity (metabolic equivalent tasks (MET)-hour/week) at baseline
  < 35202 (51.3)100 (50.8)102 (51.8)
  ≥ 35192 (48.7)97 (49.2)95 (48.2)
Education level at baseline
  < BAC39 (9.9)22 (11.2)17 (8.6)
 BAC to BAC + 2192 (48.7)98 (49.7)94 (47.7)
  ≥ BAC + 2163 (41.4)77 (39.1)86 (43.7)
Personal history of benign breast disease at baseline
 No250 (63.5)135 (68.5)115 (58.4)
 Yes144 (36.5)62 (31.5)82 (41.6)
Family history of breast cancer
 None281 (71.3)146 (74.1)135 (68.5)
 In first-degree relatives61 (15.5)31 (15.7)30 (15.2)
 In extended relatives52 (13.2)20 (10.2)32 (16.3)
Parity and age at first full-term pregnancy (FFTP)
 No children57 (14.5)22 (11.2)35 (17.8)
 1 or 2 children and < 30 years old at FFTP194 (49.2)97 (49.2)97 (49.2)
  ≥ 3 children and < 30 years old at FFTP108 (27.4)62 (31.5)46 (23.4)
  ≥ 30 years old at FFTP35 (8.9)16 (8.1)19 (9.6)
Total breastfeeding duration
 Never152 (38.6)79 (40.1)73 (37.1)
  ≤ 6 months164 (41.6)85 (43.1)79 (40.1)
  > 6 months78 (19.8)33 (16.8)45 (22.8)
Age at menarche
  < 13 years178 (45.2)95 (48.2)83 (42.1)
  ≥ 13 years216 (54.8)102 (51.8)114 (57.9)
Current use of menopausal hormone therapy at baseline
 No234 (59.7)119 (60.7)115 (58.7)
 Yes158 (40.1)77 (39.1)81 (41.1)
Use of oral contraceptives at baseline
 Never150 (38.1)79 (40.1)71 (36.0)
 Ever244 (61.9)118 (59.9)126 (64.0)
Adherence score to the Healthy dietary pattern
  < median197 (50.0)89 (45.2)108 (54.8)
  > median197 (50.0)108 (54.8)89 (45.2)
Adherence score to the Western dietary pattern
  < median197 (50.0)98 (49.7)99 (50.3)
  > median197 (50.0)99 (50.3)98 (49.7)