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Table 1 Characteristics of participants, overall and according to NSAID exposure at the end of follow-up (E3N cohort, 2004–2014)

From: Use of nonsteroidal anti-inflammatory drugs and breast cancer risk in a prospective cohort of postmenopausal women

Characteristics at the end of follow-up1 All women (n = 62,512) NSAID exposure at the end of follow-up
Never/occasional users (n = 24,019) Recurrent users (n = 38,493)
Sociodemographic factors
Age (years), mean (SD) 72.1 (6.7) 71.8 (6.7) 72.2 (6.2)
Educational level, N (%)
  < High school 6516 (10) 2160 (9) 4356 (11)
  From high school to 4 years higher education 45,138 (72) 17,450 (73) 27,688 (72)
  At least 5 years higher education 10,858 (18) 4409 (18) 6449 (17)
Lifestyle factors, N (%)
BMI (kg/m2)
  < 18.5 2626 (4) 1284 (5) 1342 (3)
  [18.5–23[ 25,409 (41) 10,913 (45) 14,496 (38)
  [23–25[ 13,197 (21) 5020 (21) 8177 (21)
  [25–30[ 16,139 (26) 5359 (22) 10,780 (28)
  ≥ 30 5141 (8) 1443 (6) 3698 (10)
Physical activity (Met-h/week)
  ≤ 34.8 15,649 (25) 5863 (24) 9786 (25)
  ]34.8–57.6] 15,680 (25) 5986 (25) 9694 (25)
  ]57.6–88.8] 15,567 (25) 6085 (25) 9482 (25)
  > 88.8 15,616 (25) 6085 (25) 9531 (25)
Smoking status
  Never smoker 33,281 (53) 13,258 (55) 20,023 (52)
  Current smoker 4741 (8) 1681 (7) 3060 (8)
  Past smoker 24,490 (39) 9080 (38) 15,410 (40)
Alcohol intake (g/day)
  Abstainer 7832 (13) 3283 (14) 4549 (12)
  ≤ 5 16,796 (27) 6611 (28) 10,185 (26)
  ]5–10] 9357 (15) 3752 (16) 5605 (15)
  ]10–20] 12,053 (19) 4546 (19) 7507 (20)
  > 20 12,522 (20) 4483 (19) 8039 (21)
  Missing 3952 (6) 1344 (6) 2608 (7)
Reproductive factors
Breastfeeding, N (%)
  Never 23,425 (37) 9088 (38) 14,337 (37)
  Ever 34,174 (55) 13,248 (55) 20,926 (54)
  Missing 4913 (8) 1683 (7) 3230 (9)
Age at menopause (years), mean (SD) 50.52 (3.73) 50.68 (3.68) 50.41 (3.76)
Age at menarche (years), N (%)
  < 13 28,078 (45) 10,413 (43) 17,665 (46)
  ≥ 13 34,434 (55) 13,606 (57) 20,828 (54)
Parity and age at first full-term pregnancy, N (%)
  Nulliparous 7282 (12) 3010 (13) 4272 (11)
  First child before age 30 years, one or two children 31,393 (50) 11,739 (49) 19,654 (51)
  First child before age 30 years, three or more children 17,373 (28) 6602 (27) 10,771 (28)
  First child after age 30 years 6464 (10) 2668 (11) 3796 (10)
Ever use of oral contraceptives, N (%) 38,570 (62) 14,191 (59) 24,379 (63)
Lifetime MHT use, N (%)
  Never 17,273 (28) 8076 (34) 9197 (24)
  Recent 5300 (8) 1866 (8) 3434 (9)
  Past 39,939 (64) 14,077 (59) 25,862 (67)
Medical events and medical follow-up, N (%)
Number of medical consultations/visits during the preceding 6 months
  0 3277 (5) 1928 (8) 1349 (4)
  [1–4[ 25,413 (41) 11,387 (47) 14,026 (36)
  ≥ 4 33,491 (54) 10,434 (43) 23,057 (60)
  Missing 331 (1) 270 (1) 61 (0)
Self-report of a mammogram performed during the previous follow-up cycle 51,097 (82) 19,194 (80) 31,903 (83)
Personal history of benign breast disease 23,268 (37) 8483 (35) 14,785 (38)
History of breast cancer in first-degree relatives 7139 (11) 2735 (11) 4404 (11)
Recurrent use2 of other drugs, N (%)
Systemic glucocorticoids 17,391 (28) 3551 (15) 13,840 (36)
Paracetamol 38,392 (61) 10,527 (44) 27,865 (72)
Proton pump inhibitors 30,063 (48) 6308 (26) 23,755 (62)
Anti-arthritics 26,400 (42) 6471 (27) 19,929 (52)
Comorbidities, N (%)
History of arthrosis 21,475 (34) 5568 (23) 15,907 (41)
History of rheumatism 6111 (10) 2400 (10) 3711 (10)
History of arthritis 888 (1) 248 (1) 640 (2)
History of polyarthritis 2375 (4) 451 (2) 1924 (5)
History of spondyloarthritis 236 (1) 29 (1) 207 (1)
History of migraine 21,591 (35) 7073 (29) 14,518 (38)
  1. Abbreviations: BMI body mass index, MET-h metabolic equivalent task-hour, MHT menopausal hormone therapy, NSAID nonsteroidal anti-inflammatory drug, SD standard deviation
  2. 1Except for years of schooling, physical activity level, age at menarche, parity and age at first birth, lifetime use of oral contraceptives, history of breast cancer in first-degree relatives, and age at menopause, which were assessed before the start of follow-up
  3. 2At least two reimbursements during any previous 3-month period since January 1, 2004