Table 1.
Abstinence and Treatment Engagement Outcomes by Treatment Group
| Primary Abstinence Outcome and Key Treatment Engagement Outcomes | ||||
|---|---|---|---|---|
|
Primary or Key Outcome
|
||||
|
Primary Abstinence Outcome: Post-Enrollment Abstinence at the 6-Month Follow-up Based on Biochemical Testa Intention-to-Treat (ITT) Sample (N=1900) |
Abstinence Rates, N Abstinent/Total (%) |
Abstinence Risk Difference (95% CI), P-Valuec |
Unadjusted Odds Ratio (95% Cl)d |
|
| Control | Incentive | Control vs. Incentive | Control vs. Incentive | |
|
| ||||
| 131/952 (13.76%) |
206/948 (21.62%) |
−7.86 (−11.28 to −4.5) P<.0001 |
0.58 (0.46 to 0.74) |
|
|
| ||||
| Key Treatment Engagement Outcomes: | Mean (SD) | t-test (df) | P-Value | |
|
| ||||
| Control | Incentive | |||
|
|
||||
| Number of Proactive Treatment Calls Taken | 2.9 (1.5) | 3.8 (1.4) | t(1898)= −14.6 | <.0001 |
| Total Number of Minutes of Counseling | 46.1 (26.5) | 65.2 (27.1) | t(1898)= −15.6 | <.0001 |
|
| ||||
| Secondary Abstinence Outcomes | ||||
|
| ||||
|
Secondary Post-Enrollment Abstinence Measure At 6-Months Follow-up |
Abstinence Rates, N Abstinent/Total (%) |
Abstinence Risk Difference (95% CI), P-Valuec |
Unadjusted Odds Ratio (95% Cl)d |
|
| Control | Incentive | Control vs. Incentive | Control vs. Incentive | |
|
| ||||
| Abstinence Based on Biochemical Test, Responder Only Sample (N=1114) |
131/562 (23.31%) |
205/552 (37.14%) |
−13.83 (−19.16 to −8.49) P<.0001 |
0.52 (0.40 to 0.67) |
| Abstinence Based on Biochemical Test, ITT Sample Removing Participants Disenrolled from Medicaid (N=1710) |
127/848 (14.98%) |
196/862 (22.74%) |
−7.76 (−11.45 to −4.07) P<.0001 |
0.60 (0.47 to 0.77) |
| Abstinence Based on Biochemical Test, ITT Sample Participants Tested with Carbon Monoxide Breath Test (N=1458) |
118/736 (16.03%) |
173/722 (23.96%) |
−7.93 (−12.02 to −3.84) P=.0002 |
0.61 (0.47 to 0.79) |
| Abstinence Based on Biochemical Test, ITT Sample Participants Tested with Urine Cotinine Test (N=384) |
10/188 (5.32% |
26/170 13.27% |
−7.95 (−13.68 to −2.22) P=.0076 |
0.37 (0.17 to 0.78) |
| Abstinence Based on Biochemical Test, ITT Sample Participants from the Quitline-Community-Based Referral (N=1456 |
119/732 (16.26%) |
174/724 (24.03%) |
−7.78 (−11.9 to −3.67) P=.0002 |
0.61 (0.47 to 0.80) |
| Abstinence Based on Biochemical Test, ITT Sample Participants from the Clinic-Based Referral (N=444) |
12/220 (5.45%) |
31/224 (13.84%) |
−8.38 (−13.81 to −2.96) P=.0029 |
0.36 (0.18 to 0.72) |
| Abstinence Based on Self-Report,b ITT Sample (N=1900) |
98/952 (10.29%) |
136/948 (14.35%) |
−4.05 (−7.00 to −1.10) P=.0072 |
0.69 (0.52 to 0.90) |
| Abstinence Based on Self-Report, Responder Only Sample (N=862) |
98/411 (23.84%) |
136/451 (30.16%) |
−6.31 (−12.22 to −0.40) P=.0374 |
0.73 (0.54 to 0.98) |
| Abstinence Based on Combined Biochemical Test and Self-Report, ITT Sample (N=1900) |
39/952 (4.10%) |
72/948 (7.59%) |
−3.50 (−5.60 to −1.39) P=.0012 |
0.52 (0.35 to 0.78) |
| Abstinence Based on Combined Biochemical Test and Self-Report, Responder Only Sample (N=651) |
39/326 (11.96%) |
72/325 (22.15%) |
−10.19 (−15.92 to −4.46) P=.0005 |
0.48 (0.31 to 0.73) |
Biochemical Test of Abstinence at the 6-month follow-up visit based on breath carbon monoxide test (n=1458; 77%), urine cotinine testing (n=384; 20%), or urine test strip (n=58; 3%).
Abstinence self-report was assessed during the 6-month follow-up call.
Pairwise comparisons of Abstinence Risk Differences were tested via Proc Freq (SAS Institute) by specifying the RISKDIFF option which provides standard Wald asymptotic confidence limits for the risks.
Unadjusted odds ratios based on logistic regression analysis.
Note: Table 1 provides absolute and relative effect sizes. Absolute effect sizes are presented as group-specific abstinence rates along with odds ratios (and 95% confidence intervals) as the effect size for the group comparison. Relative effect sizes are presented as abstinence Risk Differences with 95% confidence intervals