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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