Table 3: Association of demographic, socioeconomic, and lifestyle factors with GERD; age-adjusted and multivariable-adjusted odds ratios (ORs) from binary logistic regression.

Variable Model 1aModel 2bModel 3c
OR (95% CI)P OR (95% CI)P OR (95% CI)P

Sex
 Men
 Women
1.27 (0.83–1.94)
1.00 (reference)
0.2701.36 (0.88–2.10)
1.00 (reference)
0.1680.32 (0.17–0.59)
1.00 (reference)
<0.001
Age
 ≤40 years
 >40 years
1.00 (reference)
1.56 (0.92–2.65)
0.0991.00 (reference)
1.89 (0.96–3.76)
0.067
Educational level0.147 (2) d0.063 (2)
 Low (0–8) years1.94 (1.08–3.51)0.0282.06 (1.12–3.77)0.020
 Middle (9–12) years1.42 (0.87–2.33)0.1621.45 (0.87–2.39)0.151
 High (≥13 years)1.00 (reference)1.00 (reference)
Income level0.655 (2)0.854 (2)
 Low1.41 (0.67–2.96)0.3711.22 (0.57–2.59)0.612
 Middle1.22 (0.70–2.13)0.4831.15 (0.66–2.02)0.622
 High1.00 (reference)1.00 (reference)
BMI<0.001 (2)<0.001 (2)0.002 (2)
 <251.00 (reference)1.00 (reference)1.00 (reference)
 25–29.91.79 (1.00–3.21)0.0501.58 (0.87–2.85)0.1301.71 (0.86–3.38)0.124
 ≥303.97 (2.12–7.41)<0.0013.74 (1.99–7.01)<0.0013.79 (1.79–8.03)<0.001
Smoking<0.001 (2)<0.001 (2)<0.001 (2)
 Current smoker13.36 (7.7–23.2)<0.00123.6 (12.3–45.3)<0.00129.3 (13.9–61.2)<0.001
 Former smoker6.03 (3.06–11.8)<0.00112.68 (5.9–27.2)<0.0019.79 (4.22–22.7)<0.001
 Never smoker1.00 (reference)1.00 (reference)1.00 (reference)
Alcohol consumption
 No/Occasional intake
 Moderate/Heavy intake
1.00 (reference)
1.79 (1.13–2.83)
0.013
1.00 (reference)
1.83 (1.10–3.06)
0.021
Physical activity<0.001(2)<0.001 (2)<0.001 (2)
 Low5.79 (2.46–13.6)<0.0015.47 (2.32–12.9)<0.0017.03 (2.68–18.4)<0.001
 Moderate3.10 (1.37–7.01)0.0073.01 (1.33–6.84)0.0082.75 (1.11–6.78)0.028
 High1.00 (reference)1.00 (reference)1.00 (reference)
Fried food frequency<0.001 (2)<0.001 (2)0.001 (2)
 Frequent4.13 (2.28–7.48)<0.0013.57 (1.97–6.49)<0.0013.01 (1.52–6.20)0.002
 Moderate1.91 (0.99–3.69)0.0551.69 (0.86–3.32)0.1281.21 (0.55–2.65)0.634
 Not frequent1.00 (reference)1.00 (reference)1.00 (reference)
Meat consumption frequency0.057 (2)0.060 (2)
 Frequent3.52 (0.83–14.8)0.0873.93 (0.91–17.0)0.068
 Moderate1.79 (0.36–8.81)0.4762.09 (0.41–10.6)0.372
 Not frequent1.00 (reference)1.00 (reference)

Model 1: adjusted for age.
Model 2: simultaneously adjusted for age, sex, and socioeconomic variables (education and income level).
Model 3: adjusted for age, sex, socioeconomic variables, and behavioral factors (smoking, alcohol intake, physical activity, frequency of meat consumption, frequency of fired food consumption, and body mass index). All variables were entered in a backward stepwise elimination procedure with a P value to exit set at <0.10. Empty cells refer to the variables excluded from the final model.
Overall P value and degrees of freedom (in parentheses).