Table 3.

Smoking behavior and biomarkers of exposure while smoking reduced nicotine cigarettes means

Baseline–week 2 (usual)Week 14 (4 mg)Week 26 (1 mg)
Control (N = 50)Control (N = 50)Control (N = 40)
Research (N = 53)Research (N = 53)Research (N = 53)
CharacteristicResearch (compliant; N = 42)Research (compliant; N = 42)Research (compliant; N = 42)Significant effects P < 0.0166
Cigarettes per dayb19 (17–21)21 (18–23)22 (19–25)W26 vs. W14: R
22 (20–24)24 (21–27)20 (17–23)W26 vs. W2: R vs. C
22 (19–25)24 (21–28)20 (17–24)W26 vs. W14: R vs. C
Plasma nicotine,b ng/mL17 (14–20)18 (15–21)16 (13–19)W14 vs. W2: R
15 (13–17)10 (8–11)7 (5–10)W26 vs. W2: R
15 (13–17)9 (7–11)4 (3–6)W14 vs. W2: R vs. C
W26 vs. W2: R vs. C
Plasma cotinine,b ng/mL256 (220–293)255 (218–292)240 (202–278)W14 vs. W2: R
256 (225–287)131 (106–202)113 (81–145)W26 vs. W2: R
252 (215–289)121 (92–152)76 (49–105)W14 vs. W2: R vs. C
W26 vs. W2: R vs. C
Expired CO,b ppm20 (18–23)24 (20–27)20 (18–23)W14 vs. W2: R
21 (19–24)25 (22–28)23 (19–27)
21 (18–24)25 (21–28)22 (19–27)
Urine,a pmoL/mg creatinine
Total NNAL1.0 (0.7–1.3)0.9 (0.7–1.2)0.9 (0.6–1.2)W26 vs. W2: R
1.4 (1.1–1.7)1.2 (1.0–1.5)0.8 (0.5–1.1)W26 vs. W14: R
1.3 (1.0–1.6)1.2 (1.0–1.4)0.7 (0.5–0.9)W26 vs. W2: R vs. C
W26 vs. W14: vs. C
Sum of phens3.5 (2.8–4.4)3.5 (2.9–4.4)4.0 (3.3–4.7)NS
4.0 (3.3–4.7)3.8 (3.3–4.3)3.9 (3.1–4.8)
3.7 (3.1–4.5)3.5 (3.0–4.0)4.0 (3.1–5.2)
2-Naphthol97 (73–129)91 (66–127)112 (92–136)NS
161 (123–210)142 (113–180)137 (107–174)
166 (122–227)137 (104–179)151 (119–192)
Sum of fluors13 (10–17)12 (9–17)15 (12–18)NS
17 (14–22)18 (15–22)17 (13–23)
17 (14–22)18 (14–22)20 (15–26)
1-Hydroxypyrene1.1 (0.9–1.5)1.2 (0.9–1.6)1.4 (1.1–1.6)NS
1.4 (1.1–1.7)1.4 (1.2–1.6)1.5 (1.2–1.9)
1.3 (1.1–1.7)1.3 (1.1–1.5)1.6 (1.2–2.1)

Abbreviations: C, Control; R, RNC.

  • aGeometric means.

  • bArthimetic mean (95% CI).