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Table 1 Odds ratio (OR) for cases and controls according to hair dyes use and regular exercise after multiple imputation

From: Does hair dye use really increase the risk of prostate cancer?

Variables Cases
N = 296
Controls
N = 296
Crude OR (95% CI) AOR (95% CI)a AOR (95% CI)b
N (%) N (%)
Hair dyes
 No 201 (67.91) 231 (78.04) 1 1 1
 Yes 95 (32.09) 65 (21.96) 1.62 (1.12–2.34)* 1.75 (1.16–2.63)** 1.93 (1.17–3.17)*
Age of first use (yrs)
 Never 207 (69.93) 234 (79.05) 1 1 1
  ≥ 60 27 (9.12) 22 (7.43) 1.39 (0.77–2.51) 1.18 (0.62–2.25) 1.35 (0.64–2.86)
 50 - < 60 30 (10.14) 23 (7.77) 1.47 (0.83–2.62) 2.14 (1.07–4.27)* 2.31 (1.03–5.18)*
  < 50 32 (10.81) 17 (5.74) 2.12 (1.14–3.94) 2.24 (1.17–4.26)* 1.98 (0.91–4.32)
 P for trend      < 0.01 < 0.01 < 0.05
Years of use (years)
 Never 220 (74.32) 236 (79.73) 1 1 1
  ≤ 10 39 (13.18) 38 (12.84) 1.10 (0.68–1.78) 1.23 (0.72–2.11) 1.29 (0.68–2.43)
  > 10 37 (12.50) 22 (7.43) 1.80 (1.03–3.15)* 1.90 (1.04–3.49)* 2.13 (1.03–4.41)*
 P for trend      0.05 < 0.05 < 0.05
Frequency of use (times per year)
 Never 221 (74.66) 237 (80.07) 1 1 1
  ≤ 6 40 (13.51) 33 (11.15) 1.30 (0.79–2.13) 1.42 (0.83–2.44) 1.41 (0.75–2.65)
  > 6 35 (11.82) 26 (8.78) 1.44 (0.84–2.48) 1.79 (0.98–3.31) 2.20 (1.05–4.62)*
 P for trend      0.12 < 0.05 < 0.05
Year of first use
 No 216 (72.97) 234 (79.05) 1 1 1
 After 1980 4 (1.35) 3 (1.01) 1.10 (0.67–1.78) 1.23 (0.72–2.11) 1.29 (0.67–2.43)
 Before 1980 76 (25.68) 59 (19.93) 1.80 (1.03–3.15)* 1.90 (1.04–3.48)* 2.17 (1.03–4.41)*
 P for trend      0.09 < 0.05 < 0.05
  1. Abbreviation: AOR adjusted OR, OR odds ratio, PC prostate cancer
  2. aAdjusting for age, and family history of PC, bAdjusting for age, marital status, blood type, education, family history of PC, cigarette smoking, alcohol drinking and betel nut chewing
  3. *P-value <0.05 **p-value < 0.01 ***p-value < 0.001