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. 2013 Oct 14;16(4):381–389. doi: 10.1093/ntr/ntt156

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.

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