Table 5.
Generalized Estimating Logistic Regressions for Quit History Variables (at Wave t) Predicting Cessation Outcomes (at Wave t + 1) for the Reduced Two-Wave Sample
| Quit attempt | Sustained abstinence (among attempters) | Overall outcome (sustained abstinence) | ||||
|---|---|---|---|---|---|---|
| Cessation outcomes by whether or not a quit attempt was made in the past year | ||||||
| N observations/N individuals | 6,127/4,105 | 1,888/1,616 | 5,845/3,952 | |||
| Total percent achieving the outcome | 35.4 | 20.4 | 6.6 | |||
| Made any quit attempts last year? | p < .00001 | p < .00001 | p < .00005 | |||
| No | 23.2% (ref) | 27.1% (ref) | 5.6% (ref) | |||
| Yes | 61.8%* | 15.1%* | 8.9%* | |||
| Percentage achieving each cessation outcome (among only those with an attempt in the past year) | ||||||
| N observations/N individuals | 1,930/1,556 | 1,049/868 | 1,785/1,455 | |||
| Total percent achieving the outcome | 61.8 | 15.1 | 8.9 | |||
| Time since last quit attempt ended | p < .0001 | p = .34 | p = .96 | |||
| Within last month | 67.2% (ref) | 14.4% (ref) | 9.3% (ref) | |||
| 32–181 days ago | 63.6% | 14.5% | 8.8% | |||
| 182 days to 1 year ago | 51.8%* | 17.5% | 8.5% | |||
| Length of the last quit attempt | p = .71 | p = .16 | p = .23 | |||
| Up to 7 days | 62.4% (ref) | 12.8% (ref) | 7.7% (ref) | |||
| 8–31 days | 62.1% | 15.7% | 9.3% | |||
| 32 days or longer | 59.8% | 20.5% | 11.3% | |||
| Number of quit attempts | p < .00001 | p < .005 | p = .18 | |||
| One attempt only | 52.6% (ref) | 19.6% (ref) | 9.6% (ref) | |||
| Two or more attempts | 70.1%* | 11.8%** | 8.1% | |||
| p < .05 | p = .58 | p = .18 | ||||
| 2+, last was longest | 76.5% (ref) | 14.5% (ref) | 10.8% (ref) | |||
| 2+, last was not longest | 69.3%*** | 10.8% | 7.2% | |||
| Concurrent generalized estimating equations (among only those with an attempt in the past year) | ||||||
| OR | 95% CI | OR | 95% CI | OR | 95% CI | |
| Time since last quit attempt ended | ||||||
| Within last month | Ref | p =.14 | Ref | p =.93 | Ref | p =.85 |
| 32 to 181 days ago | 0.94 | 0.74–1.19 | 0.94 | 0.59–1.48 | 0.89 | 0.59–1.36 |
| 182 days to 1 year ago | 0.76 | 0.58–1.01 | 1.02 | 0.60–1.74 | 0.89 | 0.55–1.45 |
| Length of the last quit attempt | ||||||
| Up to 7 days | Ref | p = .32 | Ref | p = .53 | Ref | p = .34 |
| 8–31 days | 1.07 | 0.86–1.35 | 1.23 | 0.79–1.91 | 1.22 | 0.81–1.83 |
| 32 days or longer | 1.24 | 0.94–1.63 | 1.29 | 0.78–2.12 | 1.40 | 0.88–2.21 |
| Number of quit attempts | ||||||
| One attempt only | Ref | p < .00001 | Ref | p < .01 | Ref | p = .30 |
| Two or more attempts | 2.14 | 1.72–2.65 | 0.57 | 0.38–0.85 | 0.82 | 0.57–1.19 |
Note. OR = odds ratio, CI = confidence intervals. Sustained abstinence is for at least 6 months; overall outcome = sustained abstinence among all smokers. All analyses are adjusted for age, sex, education, income, ethnic minority status, marital status, cohort, interwave interval, Heaviness of Smoking Index, baseline smoking frequency, and self-efficacy. Analysis predicting the outcome among those who tried is also adjusted for use of stop-smoking medications since baseline and method of quitting (cut down or cold turkey) followed on the last quit attempt at the outcome wave (wave t + 1). The full table of results including associations with the control variables may be obtained on request from the corresponding author. Significance (p) values next to the reference category represent the overall effect across categories.
*p < .001, **p < .01, ***p < .05 (referring to upper panels, generalized estimating equations analyses conducted individually on each quit history variable).