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Table 3 Odds ratios (95% CI) of breast cancer by participants characteristics before and after adjusting for the effect of all other in a multivariable model.

From: An investigation of breast cancer risk factors in Cyprus: a case control study

Risk factor Univariable1 Multivariable (N = 2020)2, 6
   OR (95%CI) p-value3 OR (95% CI) p-value3
Education Primary 1.00    
  Secondary 1.17 (0.96,1.45)   1.18 (0.94,1.48)  
  Tertiary 1.09 (0.81,1.45)   1.12 (0.81,1.53)  
  University 1.35 (1.00,1.82) 0.07 1.40 (1.00,1,95) 0.08
Marital status Married 1.00    
  Widowed/Divorced 1.08 (0.82,1.42) 0.57 1.06 (0.78,1.44) 0.84
  Single 1.55 (1.02,2.34) 0.04 1.28 (0.69,2.35) 0.43
BMI <25 1.00    
  25-30 0.80 (0.64,0.98)   0.86 (0.69,1.07)  
  ≥30 1.21 (0.96,1.53) 0.11* 1.22 (0.95,1.56) 0.14*
Family history of breast cancer No 1.00    
  Yes 1.68 (1.29,2.19) <0.001 1.64 (1.23,2.19) 0.001
Age at menarche (years) ≤11 1.00    
  12-14 0.80 (0.62,1.03)   0.82 (0.62,1.10)  
  ≥15 0.61 (0.44,0.84) <0.01 0.64 (0.45,0.92) 0.01
Age at 1st pregnancy (years) <30 1.00    
  ≥30 1.36 (1.04,1.77)   1.25 (0.93,1.68) 0.14
  Never4 1.51 (1.08,2.12) <0.01 0.93 (0.57,1.54) 0.76
Breastfeeding5 No 1.00    
  Yes 0.63 (0.45,0.89) <0.01 0.74 (0.59,0.92) 0.01
Oral contraceptive use No 1.00    
  Yes 1.03 (0.86,1.26) 0.70 1.02 (0.83,1.27) 0.84
HRT use (months) Never 1.00    
  <6 0.63 (0.42,0.95)   0.67 (0.42,1.05)  
  6-60 0.49 (0.37,0.65)   0.47 (0.35,0.64)  
  ≥60 0.50 (0.34,0.72) <0.001 0.53 (0.35,0.79) <0.001
Exercise No 1.00    
  Yes 0.86 (0.72,1.01) 0.07 0.94 (0.78, 1.13) 0.48
Smoking Never 1.00    
  Past/Current 1.24 (1.01,1.53) 0.05 1.16 (0.91,1.47) 0.23
  1. Notes: 1In all cases, models were adjusted for age. Both univariable and multivariable inferences remain largely unaffected when restricting the analyses to ages 45-64. 2Further adjusting for the effect of all other risk factors considered here. 3P-value for difference between levels of binary/nominal variables (e.g. family history) or p-value for linear trend across ordinal categorical variables (e.g. age at menarche or age at 1st pregnancy). 4The variable 'pregnancy' was not included in the multivariable model as its effect is captured accordingly by category 'never' of the variable "age at 1st pregnancy". 5Odds ratio of the combined effect of breastfeeding after adjusting for pregnancy in a logistic model with an interaction term between the two variables but no main effect for breastfeeding. 6The p-value of the Pearson χ2 goodness-of-fit test was 0.18 in the case of the full model and 0.55 for the model where only statistically significant variables were included (i.e. family history, breastfeeding, age at menarche and HRT use), in both cases suggesting a reasonable fit of the model *Evidence of non-linearity based on Likelihood Ratio Test comparing the goodness of fit of model with ordered categories Vs linear term across categories.