Table 2.
Univariate and Multivariate Associations With Validated Cessation at 1 Month
Variable | N | Smoking at 1 month (%) | Cessation at 1 month (%) | Crude OR | 95% CI | p value | Adjusted OR | 95% CI | LRT p value | ||
---|---|---|---|---|---|---|---|---|---|---|---|
Lower | Upper | Lower | Upper | ||||||||
Age (years)† | |||||||||||
<20 | 147 | 129 (87.8) | 18 (12.2) | 0.64 | 0.36 | 1.12 | 0.250* | – | – | – | – |
20–24 | 322 | 264 (82.0) | 58 (18.0) | 1.00 | – | – | – | – | – | ||
25–29 | 228 | 183 (80.3) | 45 (19.7) | 1.12 | 0.73 | 1.73 | – | – | – | ||
30–34 | 158 | 134 (84.8) | 24 (15.2) | 0.82 | 0.49 | 1.37 | – | – | – | ||
35–39 | 78 | 63 (80.8) | 15 (19.2) | 1.08 | 0.58 | 2.04 | – | – | – | ||
≥40 | 24 | 17 (70.8) | 7 (29.2) | 1.87 | 0.74 | 4.73 | – | – | – | ||
Ethnicity | |||||||||||
Other | 27 | 21 (77.8) | 6 (22.2) | 1.00 | – | – | 0.521 | – | – | – | – |
British: White | 930 | 769 (82.7) | 161 (17.3) | 0.73 | 0.29 | 1.84 | – | – | – | ||
Age full time education finished | |||||||||||
≤16 | 751 | 636 (84.7) | 115 (15.3) | 1.00 | – | – | 0.001 | 1.00 | – | – | 0.002 |
>16 | 206 | 154 (74.8) | 52 (25.2) | 1.87 | 1.29 | 2.71 | 1.82 | 1.24 | 2.67 | ||
Partner smokes | |||||||||||
No | 225 | 186 (82.7) | 39 (17.3) | 1.00 | – | – | 0.412 | – | – | – | – |
Yes | 654 | 544 (83.2) | 110 (16.8) | 0.96 | 0.65 | 1.44 | – | – | – | ||
Not applicable | 78 | 60 (76.9) | 18 (23.1) | 1.43 | 0.76 | 2.69 | – | – | – | ||
Parity | |||||||||||
≤1 | 649 | 535 (82.4) | 114 (17.6) | 1.00 | – | – | 0.919* | – | – | – | |
2 or 3 | 256 | 211 (82.4) | 45 (17.6) | 1.00 | 0.68 | 1.46 | – | – | – | ||
≥4 | 52 | 44 (84.6) | 8 (15.4) | 0.85 | 0.39 | 1.86 | – | – | - | ||
Baseline cotinine (ng × 10−1/ml) | |||||||||||
12.1 (7.8–17.6), median (IQR) | 957 | 790 (82.6) | 167 (17.4) | 0.93 | 0.90 | 0.95 | <0.001 | 0.93 | 0.90 | 0.95 | <0.001 |
BMI | |||||||||||
<18.5 | 28 | 27 (96.4) | 1 (3.6) | 0.18 | 0.02 | 1.34 | 0.987* | – | – | – | – |
18.5–24.9 | 362 | 300 (82.9) | 62 (17.1) | 1.00 | – | – | – | – | – | ||
25–29.9 | 267 | 213 (79.8) | 54 (20.2) | 1.23 | 0.82 | 1.84 | – | – | – | ||
>30 | 254 | 212 (83.5) | 42 (16.5) | 0.96 | 0.62 | 1.47 | – | – | – | ||
Missing | 46 | 38 (82.6) | 8 (17.4) | 1.02 | 0.45 | 2.29 | – | – | – | ||
Length of first behavioral support session | |||||||||||
16–30 | 143 | 123 (86.0) | 20 (14.0) | 1.00 | – | – | 0.478 | – | – | – | – |
31–45 | 791 | 648 (81.9) | 143 (18.1) | 1.36 | 0.82 | 2.25 | – | – | – | ||
>60 | 23 | 19 (82.6) | 4 (17.4) | 1.29 | 0.40 | 4.20 | – | – | – | ||
Previous preterm births | |||||||||||
0 | 872 | 718 (82.3) | 154 (17.7) | 1.00 | – | – | 0.577 | – | – | – | – |
≥1 | 85 | 72 (84.7) | 13 (15.3) | 0.84 | 0.45 | 1.56 | – | – | – | ||
Use of NRT since pregnancy began | |||||||||||
No | 914 | 756 (82.7) | 158 (17.3) | 1.00 | – | – | 0.548 | – | – | – | – |
Yes | 43 | 34 (79.1) | 9 (20.9) | 1.27 | 0.60 | 2.69 | – | – | – | ||
Trial recruitment site | |||||||||||
Site 1 | 102 | 81 (79.4) | 21 (20.6) | 1.00 | – | – | 0.032 | – | – | – | – |
Site 2 | 113 | 97 (85.8) | 16 (14.2) | 0.64 | 0.31 | 1.30 | – | – | – | ||
Site 3 | 188 | 151 (80.3) | 37 (19.7) | 0.95 | 0.52 | 1.72 | – | – | – | ||
Site 4 | 238 | 212 (89.1) | 26 (10.9) | 0.47 | 0.25 | 0.89 | – | – | – | ||
Site 5 | 165 | 127 (77.0) | 38 (23.0) | 1.15 | 0.63 | 2.11 | – | – | – | ||
Site 6 | 77 | 63 (81.8) | 14 (18.2) | 0.86 | 0.40 | 1.82 | – | – | – | ||
Site 7 | 74 | 59 (79.7) | 15 (20.3) | 0.98 | 0.47 | 2.06 | – | – | – | ||
Gestational age (weeks) | |||||||||||
12–19 | 766 | 637 (83.2) | 129 (16.8) | 1.00 | – | – | 0.326 | – | – | – | – |
20–24 | 191 | 153 (80.1) | 38 (19.9) | 1.23 | 0.82 | 1.83 | – | – | – |
Note. BMI = body mass index; CI = confidence interval; IQR = interquartile range; LRT = likelihood ratio test; NRT = nicotine replacement therapy; OR = odds ratio.
*p value: test for trend.
†Age included as continuous variable in multivariate model to derive p value, equivalent to test for trend adjusting for covariates.