Table 2.

Weighted average (95% CI) of ratio of RNC divided by baseline UBC values for CPD, CO, and cotinine, respectively, for studies associated with graduala and immediateb reduction in nicotine and UBCsc

StudySummaryBaselineTime 1Time 2Time 3Time 4Time 5Time 6P valued
CPD
 Weighted average (95% CI)Gradual1.06 (1.00–1.13)1.09 (1.02–1.16)1.05 (0.98–1.13)0.94 (0.84–1.03)0.85 (0.75–0.95)0.003
 Weighted average (95% CI)Immediate1.09 (1.05–1.13)1.05 (1.01–1.10)0.98 (0.93–1.04)0.95 (0.89–1.00)0.89 (0.83–0.94)0.83 (0.78–0.89)<0.001
 Weighted average (95% CI)Usual brand1.08 (1.03–1.12)1.15 (1.1–1.2)1.13 (1.07–1.19)1.16 (1.1–1.22)1.17 (1.11–1.23)1.19 (1.12–1.26)<0.001
CO
 Weighted average (95% CI)Gradual1.08 (0.98–1.19)1.04 (0.93–1.15)1.01 (0.89–1.14)0.91 (0.8–1.03)0.97 (0.83–1.11)0.687
 Weighted average (95% CI)Immediate1.04 (0.97–1.11)1.09 (1.01–1.17)1.02 (0.93–1.10)0.99 (0.90–1.07)0.94 (0.86–1.02)0.94 (0.85–1.02)0.157
 Weighted average (95% CI)Usual brand1.08 (0.99–1.18)1.12 (1.01–1.22)1.07 (0.96–1.19)1.06 (0.94–1.17)1.14 (1.03–1.24)1.05 (0.94–1.16)0.353
Cotinine
 Weighted average (95% CI)Gradual0.96 (0.86–1.06)0.63 (0.56–0.70)0.46 (0.39–0.53)0.41 (0.33–0.49)0.38 (0.29–0.47)<0.001
 Weighted average (95% CI)Immediate0.36 (0.29–0.43)0.30 (0.23–0.37)<0.001
 Weighted average (95% CI)Usual brand1.07 (0.97–1.16)0.95 (0.82–1.08)0.445
  • aBenowitz et al. (5) weekly reduction schedule (with Time 1 serving as baseline) and Benowitz et al. (8) monthly reduction schedule (with Times 5 and 6 at the lowest dose); nicotine yields were 0.8–0.9, 0.6, 0.3–0.4, 0.2, and 0.1 mg FTC.

  • bHatsukami et al. (6), Hatsukami et al. (7), E.C. Donny (unpublished data); study time points are weekly with nicotine yields <0.1 mg. Cotinine was only assessed at baseline, weeks 2, and 6.

  • cBenowitz et al. (8), E.C. Donny (unpublished data).

  • dSignificance of mean ratio, assessed at the final time point as compared with 1.