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Table 1 Baseline characteristics of study participants used for the gene-specific screening for CpG sites, differentially methylated according to urinary 8-isoprostane levels

From: The associations of DNA methylation alterations in oxidative stress-related genes with cancer incidence and mortality outcomes: a population-based cohort study

Characteristics Derivation set (n = 1000) 1st validation set (n = 548) 2nd validation set (n = 741) P value#
Age (year, median, IQR) 62 (57–67) 62 (57–67) 62 (56–67) 0.30
Sex (n, %)     < 0.001
 Female 500 (50.0) 324 (61.0) 415 (56.0)  
 Male 500 (50.0) 224 (39.0) 326 (44.0)  
Education (n, %)     0.95
 < 9 years 737 (73.7) 411 (75.0) 548 (74.0)  
 9–11 years 155 (15.5) 85 (15.5) 115 (15.5)  
 > 12 years 108 (10.8) 52 (9.5) 78 (10.5)  
Smoking status (n, %)     0.19
 Never smoker 481 (48.1) 257 (46.9) 363 (49.0)  
 Former smoker who quitted > 20 years ago 124 (12.4) 74 (13.5) 112 (15.1)  
 Former smoker who quitted 5 to < 20 years ago 149 (14.9) 83 (15.2) 100 (13.5)  
 Former smoker who quitted 0 to < 5 years ago 60 (6.0) 29 (5.3) 31 (4.2)  
 Current smoker smoking 0 to < 15 g tobacco/day 84 (8.4) 49 (8.9) 60 (8.1)  
 Current smoker smoking 15 to < 30 g tobacco/day 97 (9.7) 49 (8.9) 60 (8.1)  
 Current smoker smoking > 30 g tobacco/day 5 (0.5) 7 (1.3) 15 (2.0)  
Alcohol consumption (g/day, median, IQR) 6.0 (0–14.4) 5.6 (0–12.6) 4.8 (0–13.7) 0.80
Physical activity (n, %)     0.17
 Inactive 204 (20.4) 114 (20.8) 157 (21.2)  
 Sedentary 438 (43.8) 270 (49.3) 343 (46.3)  
 Vigorously active 358 (35.8) 164 (39.9) 241 (32.5)  
BMI (kg/m2, median, IQR) 27.4 (25.0–30.1) 27.1 (24.5–30.1) 27.2 (24.9–30.1) 0.39
Categorized BMI (n, %)     < 0.001
 < 25 kg/m2 251 (25.1) 167 (30.5) 195 (26.3)  
 25 to < 30 kg/m2 483 (48.3) 235 (42.9) 350 (47.2)  
 ≥ 30 kg/m2 266 (26.6) 146 (26.6) 196 (26.5)  
Dietary factors (n, %)
 Fruit consumption, < once/day 391 (39.2) 192 (35.0) 287 (38.7) 0.26
 Vegetable consumption, < once/day 656 (65.6) 341 (62.2) 461 (62.2) 0.25
 Meat consumption, ≥ once/day 349 (34.9) 178 (31.5) 247 (33.3) 0.59
Leukocyte composition (mean, SD)
 CD8+ T cells 0.07 (0.05–0.10) 0.09 (0.07–0.12) 0.06 (0.04–0.09) < 0.001
 CD4+ T cells 0.16 (0.12–0.20) 0.17 (0.13–0.20) 0.16 (0.12–0.20) 0.01
 NK cells 0.91 (0.07–0.12) 0.09 (0.07–0.12) 0.10 (0.07–0.13) 0.18
 B cells 0.06 (0.05–0.07) 0.07 (0.06–0.08) 0.06 (0.04–0.07) < 0.001
 Monocytes 0.10 (0.09–0.11) 0.10 (0.09–0.11) 0.07 (0.06–0.08) < 0.001
 Granulocytes 0.55 (0.48–0.60) 0.54 (0.47–0.59) 0.56 (0.50–0.62) < 0.001
8-isoprostane (nmol/mmol creatinine, median, IQR) 0.19 (0.13–0.26) 0.21 (0.16–0.27) 0.21 (0.16–0.28) < 0.001
Prevalent cancer cases (n, %) 75 (7.5) 32 (6.0) 57 (7.7) 0.46
Prevalent CVD cases (n, %) ^ 218 (21.8) 107 (20.2) 137 (18.5) 0.24
Prevalent diabetes cases (n, %) 155 (15.5) 89 (16.8) 108 (14.6) 0.64
Prevalent asthma cases (n, %) 74 (7.4) 23 (4.3) 49 (6.6) 0.19
  1. Abbreviations: BMI body mass index, CVD cardiovascular disease, IQR interquartile range
  2. #Differences in baseline characteristics among the three groups were assessed with a Wilcoxon signed-rank test for continuous variables and a chi-square test for categorical variables
  3. The consumption of alcohol was calculated by the following equation: 1 bottle of beer = 11.88 g ethanol, 1 glass of wine = 22.0 g ethanol, 1 shot of liquor = 6.4 g ethanol
  4. Definition of inactive: < 1 h of physical activity/week. Definition of medium or high physical activity: ≥ 2 h of vigorous and ≥ 2 h of light physical activity/week. Definition of low physical activity: all other amounts of activity not categorized as “inactive” or “medium or high”
  5. Estimated by the Houseman algorithm
  6. ^Cardiovascular disease at baseline is a composite variable of either coronary heart disease or history of one or more cardiovascular event (i.e., stroke, myocardial infarction, pulmonary embolism, bypass operation, or dilatation of the coronary vessels)