Table 5 Three multivariable models demonstrating predictors of three types of smoking habits, Tehran, 2013–2015

Lifetime waterpipe smoking

1.65 (1.15–2.36)

–

1.47 (1.12–1.91)

0.005

Lifetime exposure to second hand smoking

1.19 (0.85–1.66)

1.47 (1.13–1.92)

–

Cigarette Smoking (Lifetime vs. never)

–

1.55 (1.08–2.21)

1.08 (0.77–1.50)

0.663

 Never

1

1

1

–

 1–50

6.67 (2.52–17.64)

1.70 (0.76–4.22)

1.15 (0.53–2.50)

0.716

 51–500

2.98 (1.26–7.07)

1.64 (0.81–3.81)

0.76 (0.38–1.53)

0.444

  > 500

7.84 (3.45–17.85)

0.75 (0.42–1.48)

1.15 (0.64–2.09)

0.632

 Test for trend

2.04 (1.61–2.59)

0.99 (0.81–1.20)

1.01 (0.85–1.21)

0.881

 Never

1

1

–

  ≤ 500

4.52 (2.80–7.29)

2.86 (1.86–4.40)

1.22 (0.81–1.84)

0.334

 500–5000

4.54 (2.77–7.46)

3.93 (2.50–6.18)

1.33 (0.86–2.05)

0.196

  > 5000

5.71 (3.49–9.34)

3.55 (2.23–5.67)

1.76 (1.14–2.72)

0.011

 Test for trend

1.88 (1.61–2.18)

1.65 (1.43–1.91)

1.19 (1.04–1.37)

0.009

 History of depression

1.81 (1.22–2.70)

1.78 (1.30–2.44)

1.46 (1.14–1.89)

0.003

 0

1

1

1

–

 1–2

1.77 (1.08–2.88)

1.05 (0.74–1.52)

1.32 (0.99–1.76)

0.059

  > 3

1.94 (1.15–3.29)

1.28 (0.85–1.91)

1.99 (1.44–2.75)

< 0.001

 Test for trend

1.32 (1.04–1.69)

1.14 (0.94–1.39)

1.42 (1.21–1.67)

< 0.001

  > 20

1

1

1

–

 20–29.999

3.26 (1.51–7.03)

1.70 (1.05–2.74)

1.31 (1.04–2.60)

0.173

 30–39.999

3.77 (1.75–8.13)

0.86 (0.53–1.41)

1.10 (0.52–1.36)

0.646

 40–50

5.27 (2.37–11.72)

0.25 (0.14–0.47)

1.26 (0.75–1.74)

0.293

 Male sex

6.01 (3.12–8.77)

2.47 (1.83–3.34)

0.54 (0.42–0.70)

< 0.001

 Years of education

0.96 (0.91–1.01)

0.99 (0.94–1.03)

0.92 (0.89–0.95)

< 0.001