F2RL3 Methylation as a Biomarker of Current and Lifetime Smoking Exposures

http://dx.doi.org/10.1289/ehp.1306937

Table 1. Baseline characteristics and F2RL3 (CpG_4) methyla­tion intensity of the study population.
Characteristic n (%) Methylation intensity
Median (Q1–Q3) p‑Valuea
Q, quartile.
aKruskal–Wallis test for group differences. bData missing for 9 participants. cData missing for 97 participants. dData missing for 329 participants. eData missing for 9 participants; categories defined as follows: inactive, < 1 hr/week of physical activity; medium/high: ≥ 2 hr/week of vigorous physical activity or ≥ 2 hr/week of light physical activity; low, other. fData missing for 6 participants. gData missing for 1 participant. hData missing for 3 participants. iData missing for 102 participants.
Overall 3,588 (100) 0.79 (0.72–0.84)  
Sex      
Male 1,594 (44.4) 0.77 (0.66–0.82)  
Female 1,994 (55.6) 0.80 (0.75–0.84) < 0.0001
Age (years)      
50–59 1,265 (35.3) 0.79 (0.69–0.84)  
60–64 1,025 (28.6) 0.80 (0.72–0.84)  
65–69 789 (22.0) 0.79 (0.73–0.84)  
70–75 509 (14.2) 0.79 (0.72–0.84) 0.04
BMI (kg/m2)b      
Underweight (< 18.5) 21 (0.6) 0.71 (0.62–0.84)  
Normal weight (18.5 to < 25.0) 958 (26.8) 0.79 (0.69–0.83)  
Overweight (25.0 to < 30.0) 1,692 (47.3) 0.79 (0.73–0.84)  
Obesity (≥ 30.0) 908 (25.3) 0.79 (0.72–0.83) 0.005
Smoking statusc      
Never smoker 1,701 (48.7) 0.82 (0.78–0.85)  
Former smoker 1,136 (32.5) 0.77 (0.70–0.82)  
Current smoker 654 (18.7) 0.62 (0.53–0.73) < 0.0001
Alcohol consumption (g/day)d      
Abstainer 1,052 (32.3) 0.79 (0.71–0.84)  
Low (women, 0–19.99; men, 0–39.99) 1,963 (60.2) 0.79 (0.72–0.84)  
Intermediate (women, 20–39.99; men, 40–59.99) 191 (5.9) 0.79 (0.71–0.84)  
High (women, ≥ 40; men, ≥ 60) 53 (1.6) 0.79 (0.73–0.83) 0.96
Physical activitye      
Inactive 725 (20.3) 0.79 (0.71–0.83)  
Insufficient 1,655 (46.2) 0.79 (0.71–0.83)  
Sufficient 1,199 (33.5) 0.80 (0.74–0.84) 0.0002
Diabetesf      
Not prevalent 3,011 (84.1) 0.79 (0.72–0.84)  
Prevalent 571 (15.9) 0.78 (0.69–0.83) 0.05
Hypertensiong      
Not prevalent 1,524 (42.5) 0.79 (0.72–0.84)  
Prevalent 2,063 (57.5) 0.79 (0.71–0.83) 0.45
Cardiovascular diseaseh      
Not prevalent 2,984 (83.2) 0.79 (0.72–0.84)  
Prevalent 601 (16.8) 0.78 (0.68–0.82) < 0.0001
Canceri      
Not prevalent 3,255 (93.4) 0.79 (0.72–0.84)  
Prevalent 231 (6.6) 0.78 (0.71–0.83) 0.18