Results of Effects of Cigarette Reduction on Cardiovascular Risk Factors and Subjective Measures

SmokedRecruitment and Characteristics of Subjects

A total of 151 subjects were enrolled in this study, Of these, 102 subjects were randomized to the experimental group and 49 subjects were randomized to the wait list control (Fig 1). Among those in the wait list control, 3 patients dropped out during the wait list portion of the study and 13 patients dropped out during the reduction phase of the study. Of the participants randomized to the experimental group, no subjects dropped out prior to or during baseline measurements; a total of 25 subjects dropped out by week 6, 34 subjects by week 8, and 37 subjects by week 12 of treatment. In total, 98 of 151 subjects completed treatment through week 12, and 53 subjects dropped out. Table 2 describes the characteristics of all randomized subjects, subjects who reduced by at least 40% at week 4, from weeks 4 to 6, and from weeks 4 to 12. Logistic regression was used to compare the groups on differences in demographics and smoking history. The only significant differences among these groups were for age between all randomized subjects compared to those subjects who constituted the sample for visit 4 (p = 0.0031), visit 6 (p = 0.001), and visit 12 (p = 0.02); for years smoked between all randomized subjects and subjects who comprised the sample for visit 4 (p = 0.04) and visit 6 (p = 0.01); and for motivation to quit between all randomized subjects, compared to subjects who comprised the sample for visit 12 (p = 0.03) and between subjects who comprised the sample for visit 4 compared to visit 12 (p = 0.05). The results show that subjects who were older (odds ratio, 1.04, p = 0.02) and reported more motivation to quit (odds ratio, 1.13; p = 0.04) were more successful in sustaining reduction through week 12.

 

Reliability of Biomarkers for Disease

Data were analyzed from the subjects who were assigned to the wait list control to determine intrasubject reliability, that is the correlation coefficients across each time period (baseline visit — 1 by visit 0, visit — 1 and visit 0 by visit 4 and visit 6, visit 4 by visit 6) for all measures. Table 3 shows the correlation coefficients over time for the cardiovascular biomarkers. Correlation coefficients across the various time measurements were significant for all the measures ranging from 0.44 to 1.00.

BiomarkersReduction in Biomarkers for CVD Risk Associated With Reduction in Cigarette Smoking

Table 4 shows that significant changes were observed in a number of cardiovascular biomarkers, excluding all abstinent subjects. Within the wait list group, comparing mean values obtained during the baseline visits with values obtained during the reduction phase visit found significant differences (p < 0.05) in many of the biomarkers measured (hemoglobin, hematocrit, RBC count, WBC count, mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), triglycerides, total cholesterol, total choles-terol/high-density lipoprotein [HDL] ratio, apoli-poprotein B (ApoB), heart rate, and respiratory symptoms), suggesting that these changes were due to the effect of smoking reduction and not random fluctuations in the value of these measures. Correlation coefficients for percentage reduction in cigarettes with percentage reduction in disease risk biomarkers were calculated for all variables that showed significant decreases during the reduction phase observed in Table 4. Among all randomized subjects who completed 12 weeks of treatment, positive correlations were observed for WBC count (r = 0.26, p = 0.01), total cholesterol/HDL ratio (r = 0.25, p = 0.02), and heart rate (r = 0.21, p = 0.05).

Achievement of Reduction in Smoking and Abstinence

The mean reduction in cigarettes (baseline — week/ baseline) across the total sample who completed the study was 51.7% at week 4, 71.1% at week 6, and 62.1% at week 12. The number of individuals who were able to achieve at least 40% reduction (including abstainers) by self-report from week 4 through 12 was 64 of 151 subjects. The number of individuals who were abstinent for the past 1 month with biochemical verification (carbon monoxide < 8 ppm) was 1 of 151 subjects at 6 weeks and 9 of 151 subjects at 12 weeks. When the 26-week data were examined, 27% (41 of 151 subjects) achieved at least a 40% reduction in cigarette smoking and 7% (11 of 151 subjects) achieved biochemically verified abstinence for the past month.

Fig1

Figure 1. Flow chart of subjects randomized to a wait list group and cigarette reduction groups.

Table 2—Demographics and Smoking History

Variables All Randomized Subjects (n = 151) Week 4 (n = 107) > 40% CPD Reduction Week 6 (n = 98) > 40% CPD Reduction Week 12 (n = 64) > 40% CPD Reduction
Age, yr 44.73 ± 10.49 46.39 ± 9.48 46.86 ± 9.42 47.17 ± 9.74
Male gender 69 (45.70) 49 (45.79) 47 (47.96) 30 (46.88)
Female gender 82 (54.30) 58 (54.21) 51 (52.04) 34 (53.13)
Baseline CPD 24.16 ± 6.32 23.72 ± 5.59 23.68 ± 5.74 23.75 ± 5.74
Cotinine, ng/mL 5,174.71 ± 2,915.18 5,252.89 ± 2,909.41 5,239.83 ± 2,938.43 5,271.05 ± 3,088.85
Years of smoking 29.89 ± 10.17 30.99 ± 9.53 31.41 ± 9.50 31.71 ± 9.69
FTNDt 6.07 ± 1.91 6.15 ± 1.86 6.16 ± 1.84 6.27 ± 1.80
Number quit attempts 4.16 ± 9.29 3.38 ± 5.46 3.48 ± 5.61 3.69 ± 6.60
Motivation to quitf 6.21 ± 2.90 6.33 ± 2.83 6.43 ± 2.70 6.78 ± 2.72

Table 3—Correlation Coefficients Over Time for Biomarkers (n = 34 to 47)

Variable Mean

CorrelationRange of CorrelationsSignificanceHemoglobin0.730.59-0.87< 0.0001Hematocrit0.820.79-0.86< 0.0001RBC count0.890.86-0.91< 0.0001RBC distribution0.900.86-0.95< 0.0001WBC count0.710.64-0.84< 0.0001MCV0.970.95-0.98< 0.0001MCH0.960.95-0.97< 0.0001MCH concentration0.510.44-0.63< 0.0001 to 0.0024Triglycerides0.800.73-0.85< 0.0001Total cholesterol0.870.84-0.91< 0.0001HDL0.900.87-0.94< 0.0001LDL0.860.82-0.92< 0.0001HDL/LDL0.850.76-0.94< 0.0001Total cholesterol/HDL0.900.86-0.95< 0.0001ApoA10.820.81-0.84< 0.0001ApoB0.900.89-0.92< 0.0001Systolic BP0.790.76-0.82< 0.0001Diastolic BP0.730.70-0.77< 0.0001Heart rate0.670.50-0.78< 0.0001 to 0.0003Weight1.001.00< 0.0001Respiratory symptoms0.640.51-0.76< 0.0001 to 0.0002Carbon monoxide0.610.53-0.70< 0.0001

Table 4—Effects of Reduction in CPD on Biomarkers for Disease Risk in Smokers Who Reduced Their Self-Reported CPD by > 40% Compared to Baseline and Excluding Abstainers, at Week 4, Weeks 4 to 6, and Weeks 4 to 12

Variables Baselinef Week 4 Week 6 Week 12
CPD
Mean ± SD 24.16 ± 6.32 11.10 ± 3.03 6.57 ± 2.71 6.93 ± 4.03
No. 151 107 98 64
% change – 53.06 – 72.35 – 70.27
Hemoglobin
Mean ± SD 14.49 ± 1.13 14.41 ± 1.14 14.24 ± 1.16§ 14.40 ± 1.10!
No. 151 106 95 63
% change – 0.51 – 1.67 – 1.91
Effect size – 0.16 – 0.44 – 0.45
95% CI for effect size – 0.35 to 0.03 – 0.65 to – 0.24 – 0.70 to – 0.21
Hematocrit
Mean ± SD 42.63 ± 3.27 42.62 ± 3.39 41.91 ± 3.45§ 42.42 ± 3.32!
No. 151 106 95 63
% change – 0.15 – 1.77 2.01
Effect size – 0.05 – 0.44 – 0.45
95% CI for effect size – 0.24 to 0.14 – 0.64 to – 0.24 – 0.70 to – 0.21
RBC count
Mean ± SD 4.62 ± 0.43 4.61 ± 0.46 4.56 ± 0.46! 4.61 ± 0.41!
No. 151 106 95 63
% change – 0.05 – 1.34 – 1.58
Effect size 0.01 – 0.37 – 0.38
95% CI for effect size – 0.19 to 0.18 – 0.57 to – 0.17 – 0.63 to – 0.13
RBC distribution
Mean ± SD 13.05 ± 1.14 13.09 ± 1.45 12.99 ± 1.38 13.03 ± 1.18
No. 151 106 95 63
% change 0.03 – 0.75 – 0.07
Effect size 0.02 – 0.19 – 0.05
95% CI for effect size – 0.17 to 0.21 – 0.40 to 0.01 – 0.30 to 0.19
WBC count
Mean ± SD 7.39 ± 1.84 6.96 ± 1.92! 6.70 ± 1.85 6.98 ± 2.11
No. 151 106 95 63
% change – 5.07 – 8.09 – 7.45
Effect Size – 0.34 – 0.52 – 0.44
95% CI for effect size – 0.53 to – 0.15 – 0.72 to – 0.31 – 0.69 to – 0.19
MCV
Mean ± SD 92.50 ± 5.32 92.70 ± 5.48 92.28 ± 5.41 92.40 ± 5.24
No. 151 106 95 63
% change 0.11 – 0.43 – 0.38
Effect size 0.10 – 0.31 0.22
95% CI for effect size – 0.29 to 0.09 – 0.51 to – 0.11 – 0.47 to 0.03
MCH
Mean ± SD 31.45 ± 2.01 31.36 ± 2.04! 31.39 ± 2.08 31.38 ± 1.89
No. 151 106 95 63
% change – 0.47 – 0.33 – 0.26
Effect size – 0.30 – 0.19 – 0.13
95% CI for effect size – 0.49 to – 0.11 – 0.40 to 0.01 – 0.38 to 0.11
MCH concentration
Mean ± SD 33.98 ± 0.60 33.82 ± 0.67 34.00 ± 0.67 33.98 ± 0.62
No. 151 106 95 63
% change – 0.34 0.12 0.17
Effect size 0.21 0.02 0.04
95% CI for effect size – 0.39 to 0.00 – 0.17 to 0.21 – 0.16 to 0.24
Triglycerides
Mean ± SD 144.77 ± 97.33 145.24 ± 97.51 141.31 ± 93.67 133.27 ± 71.30
No. 148 101 91 59
% change – 0.93 – 0.14 – 0.48
Effect size – 0.17 – 0.23 0.20
95% CI for effect size – 0.36 to 0.23 – 0.44 to – 0.02 – 0.46 to 0.06
Total cholesterol
Mean ± SD 201.03 ± 38.96 200.60 ± 39.68 206.15 ± 42.00 202.67 ± 36.22
No. 149 102 91 60
% change – 1.87 0.54 – 1.45
Effect size – 0.23 0.01 – 0.23
95% CI for effect size – 0.43 to – 0.04 – 0.20 to 0.22 – 0.48 to 0.03
HDL
Mean ± SD 50.27 ± 16.98 49.48 ± 16.75 51.65 ± 17.27 52.82 ± 17.72
No. 148 101 91 60
% change 3.46 6.17 10.08
Effect Ssze 0.15 0.25 0.34
95% CI for effect size – 0.04 to 0.35 0.04 to 0.46 0.08 to 0.60
Variables Baselinef Week 4 Week 6 Week 12
LDL
Mean ± SD 122.14 ± 36.04 122.29 ± 37.16 125.76 ± 36.51 124.36 ± 32.94
No. 142 101 90 58
% change – 1.99 0.57 – 3.53
Effect size – 0.17 – 0.02 – 0.34
95% CI for effect size – 0.37 to 0.04 – 0.23 to 0.19 – 0.61 to – 0.08
HDL/LDL ratio
Mean ± SD 0.47 ± 0.29 0.47 ± 0.35 0.46 ± 0.26 0.49 ± 0.30
No. 142 101 90 58
% change 8.24 8.55 16.91
Effect size 0.25 0.20 0.41
95% CI for effect size – 0.4 to 0.45 – 0.01 to 0.41 0.15 to 0.68
Total cholesterol/HDL ratio
Mean ± SD 4.43 ± 1.77 4.42 ± 1.56 4.42 ± 1.74 4.22 ± 1.45
No. 148 101 91 60
% change – 3.66 – 2.77 – 7.77
Effect size – 0.34 – 0.23 – 0.47
95% CI for effect size – 0.53 to – 0.14 – 0.43 to – 0.02 – 0.72 to – 0.21
ApoA1
Mean ± SD 142.79 ± 30.20 141.74 ± 31.79 146.89 ± 32.27 147.55 ± 29.71
No. 148 100 91 60
% change 1.17 3.13 5.30
Effect size – 0.01 0.15 0.25
95% CI for effect size – 0.21 to 0.18 – 0.06 to 0.36 – 0.01 to 0.50
ApoB
Mean ± SD 103.74 ± 30.27 106.47 ± 30.28 107.10 ± 30.98 103.00 ± 29.20!
No. 148 100 91 60
% change – 1.20 0.13 – 4.18
Effect size – 0.13 – 0.05 – 0.40
95% CI for effect size -0.33 to 0.07 -0.26 to 0.16 -0.66 to 0.15
Systolic BP
Mean ± SD 122.97 ± 16.73 118.50 ± 17.33J 121.66 ± 16.17J 120.29 ± 15.21!
No. 150 105 98 63
% change – 3.61 – 2.03 – 2.98
Effect size – 0.30 – 0.25 – 0.26
95% CI for effect size – 0.48 to – 0.11 – 0.44 to – 0.06 – 0.46 to – 0.05
Diastolic BP
Mean ± SD 71.65 ± 10.09 70.44 ± 9.55 71.40 ± 9.56 71.03 ± 9.83
No. 150 105 98 63
% change – 2.10 – 1.52 – 2.26
Effect size – 0.15 – 0.19 – 0.18
95% CI for effect size – 0.33 to 0.03 – 0.38 to 0.00 – 0.38 to 0.02
Heart rate
Mean ± SD 75.70 ± 8.85 76.62 ± 10.26 71.74 ± 9.17§ 70.18 ± 9.70§
No. 150 105 97 63
% change – 3.86 – 4.51 – 5.50
Effect size – 0.39 – 0.52 – 0.43
95% CI for effect size – 0.57 to – 0.20 – 0.71 to – 0.33 – 0.63 to – 0.23
Weight
Mean ± SD 176.02 ± 39.65 176.41 ± 39.38 175.55 ± 37.45 176.20 ± 38.75
No. 149 105 95 64
% change – 0.29 0.16 0.32
Effect size – 0.17 0.04 0.06
95% CI for effect size – 0.36 to 0.02 – 0.16 to 0.24 – 0.18 to 0.31
Respiratory symptoms
Mean ± SD 10.64 ± 6.00 9.02 ± 6.41 7.24 ± 5.20 7.16 ± 5.68
No. 151 96 96 63
% change 0.17 – 11.66 – 12.87
Effect size – 0.21 – 0.61 – 0.52
95% CI for effect size – 0.41 to – 0.01 – 0.81 to – 0.41 -0.77 to – 0.28
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