Table 5.
Multiple linear regression results of waterpipe nicotine dependence (dependent) and waterpipe smoking status (independent).
| Variables | Values | (1) | (2) | (3) |
|---|---|---|---|---|
| WTP smoking status | Nonsmoker | −20.980∗∗ (−23.697, -18.262) | −16.847∗∗ (−21.151, −12.543) | −16.151∗∗ (−20.084, −12.219) |
| Dual user | 13.343∗∗ (9.807, 16.879) | 12.331∗∗ (7.818, 16.845) | 12.034∗∗ (6.841, 17.227) | |
| Sex | 2.169 (−2.646, 6.983) | 3.173 (−2.342, 8.688) | ||
| Grade | −0.159 (−1.864, 1.546) | 0.156 (−1.884, 2.196) | ||
| Age | 0.739 (−0.256, 1.733) | 0.343 (−0.886, 1.573) | ||
| Father's work | Blue collar | 0.866 (−14.146, 15.878) | 1.415 (−13.701, 16.531) | |
| White collar | 3.854 (−9.909, 17.618) | 4.262 (−9.396, 17.920) | ||
| Father's current employment | 1.428 (−2.468, 5.325) | 1.703 (-2.467, 5.872) | ||
| Mother's work | Blue collar | −14.172∗∗ (−15.202, −13.142) | −7.722∗∗ (−11.739, −3.704) | |
| White collar | −18.438∗∗ (−20.462, −16.414) | −11.758∗∗ (−16.840, −6.677) | ||
| Housewife | −16.800∗∗ (−22.403, −11.197) | −10.428∗ (−18.616, −2.239) | ||
| Mother's current employment | −1.823 (−8.753, 5.106) | −2.344 (−9.828, 5.140) | ||
| Family members in the household | 0.084∗ (0.031, 0.137) | 0.084∗∗ (0.041, 0.126) | ||
| Mother's smoking status | Cigarettes | 2.195∗ (0.154, 4.235) | 1.653 (−0.064, 3.369) | |
| WTP | −1.309 (−8.329, 5.711) | −1.106 (−8.584, 6.371) | ||
| Dual user | −4.292 (−12.074, 3.489) | −3.561 (−10.755, 3.632) | ||
| Father's smoking status | Cigarettes | −0.361 (−3.470, 2.748) | −0.501 (−3.436, 2.435) | |
| WTP | −0.251 (−5.479, 4.978) | 0.069 (−4.710, 4.848) | ||
| Dual user | 3.836 (−3.717, 11.390) | 3.819 (−4.593, 12.231) | ||
| Siblings' smoking status | Cigarettes | 1.249 (−0.780, 3.278) | 0.971 (−0.715, 2.657) | |
| WTP | 2.279 (−0.276, 4.833) | 2.862∗ (1.172, 4.553) | ||
| Dual user | 4.127∗ (0.947, 7.306) | 3.534∗ (0.868, 6.200) | ||
| Friends' smoking status | Cigarettes | 0.680 (−6.576, 7.935) | 0.879 (−6.649, 8.406) | |
| WTP | 5.908∗ (1.594, 10.221) | 6.011∗ (1.263, 10.758) | ||
| Dual user | 11.718∗∗ (10.554, 12.883) | 11.318∗∗ (9.630, 13.006) | ||
| Depressive symptoms | 0.784∗∗ (0.437, 1.130) | |||
| Constant | 63.759∗∗ (59.036, 68.482) | 67.983∗∗ (51.000, 84.966) | 53.324∗∗ (37.455, 69.194) |
Statistically significant ∗(p < 0.05)∗∗(p < 0.01). The table shows the point estimate, followed by the 95% confidence interval in brackets. WTP smoking status' reference value was WTP-only smoker, and the other categorical variables used the first value reported above as the reference value. The table shows the results of the regression of the dependent variable waterpipe nicotine dependence calculated from the Waterpipe Nicotine Dependence Scale. The independent variable was WTP smoking status (WTP-only smoking was used as base value). The model controlled for potential confounders: sex, age, grade [9–12], father's and mother's work (deceased, blue collar, white collar, and housemaker) and current employment as a proxy for socioeconomic status with the number of family members in the household, status of smoking for the parents, siblings, and friends (nonsmoker, cigarettes smoker, waterpipe smoker, or dual user), and depressive symptoms. The first model represents the crude unadjusted coefficient. The second model adjusts for all potential confounders except for depressive symptoms. The third model adjusts for all potential confounders considered in our study. The model is adjusted for the clusters and weights generated from the study design.