Table 2 Demographic and genetic ancestry data from groups

Age (years)^a

39.0 (8.2)

39.0 (9.7)

–

–

0.99 (0.95–1.02)

0.44

Skin phototype-N (%)

0.09

0.13

 II

18 (15)

30 (25)

1.00 (–)

1.00 (–)

 III

42 (35)

45 (38)

1.56 (0.76–3.20)

1.32 (0.57–3.02)

 IV

46 (39)

30 (25)

2.56 (1.22–5.38)

1.40 (0.58–3.39)

 V

13 (11)

14 (12)

1.55 (0.60–4.02)

0.39 (0.11–1.40)

Education level-N (%)

<0.01

0.01

 Elementary-Middle school

39 (33)

14 (12)

4.67 (2.24–9.73)

4.04 (1.62–10.11)

 High school

43 (36)

43 (36)

1.68 (0.93–3.01)

1.71 (0.85–3.44)

 College

37 (31)

62 (52)

1.00 (–)

1.00 (–)

Family with melasma (first degree)-N (%)

67 (56)

27 (24)

3.10 (1.11–8.70)

0.03

3.04 (1.56–5.94)

<0.01

Age of menarche (years)^a

12.8 (1.8)

12.7 (1.8)

1.01 (0.88–1.16)

0.92

–

–

Time using hormonal contraception (years)^b

10 (3–15)

5 (1–12)

1.03 (0.98–1.07)

0.13

1.02 (0.98–1.07)

0.33

Daily regular sun exposition-N (%)

42 (44)

24 (27)

2.15 (1.16–3.99)

0.02

1.09 (0.57–2.10)

0.80

Pregnancy history-N (%)

92 (77)

77 (65)

1.86 (1.05–3.29)

0.03

1.50 (0.69–3.29)

0.31

Psycotropic drugs (regular use)-N (%)

 Antidepressant

28 (24)

18 (15)

1.73 (0.90–3.33)

0.10

2.96 (0.37–24.03)

0.31

 Anxiolytic

11 (9)

5 (4)

2.32 (0.78–6.90)

0.12

–

–

Genetic ancestry (%)^b

 European component

77 (64–89)

82 (69–90)

0.98 (0.97–0.99)

0.04

–

–

 Amerindian component

7 (4–14)

7 (4–14)

1.00 (0.97–1.02)

0.72

–

–

 African component

10 (4–21)

6 (4–16)

1.03 (1.01–1.05)

<0.01

1.04 (1.01–1.07)

<0.01

Interactions

 Antidepressant^a Family with melasma

6.15 (1.13–33.37)

<0.01

 Antidepressant^a Pregnancy history

0.14 (0.01–1.35)

0.09