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. 2019 Apr 30;49(1):259–269. doi: 10.1093/ije/dyz096

Table 1.

Basic characteristics of study participants in the three cohort studies (NHS, NHS2, HPFS)a

Overall population Non-polyp CA-only SP-only Synchronous CA and SP
No. of participants 27 426 22 095 2952 1585 794
Age, years 63.2±10.0 63.2±10.1 64.1±9.2 60.7±9.7 64.5±8.5
Female, % 70 71 57 73 58
Genetic risk score (GRS) 30.5 (3.9) 30.5 (3.9) 31.1 (3.9) 30.8 (3.9) 31.3 (3.8)
Family history of colorectal cancer, % 22 22 27 26 27
Pack-years of smoking 10.0±16.4 9.8±16.2 10.5±17.0 14.0±20.1 16.6±21.1
 Never smokers, % 51 51 52 45 40
 Past smokers‚ <30 packs/year, % 35 35 33 33 34
 Past smokers‚ ≥30 packs/year, % 9 9 10 14 14
 Current smokers, <30 packs/year, % 2 2 2 3 3
 Current smokers‚ ≥30 packs/year, % 3 3 3 6 9
Body mass index, kg/m2 26.4±5.0 26.4±5.0 26.8±5.0 27.2±5.1 27.8±5.5
 <25, % 44 45 41 37 33
 25.0-29.9, % 37 36 38 40 38
 30.0-34.9, % 13 13 14 16 19
 ≥35, % 6 6 7 8 10
Height, cm 168.7±9.3 168.7±9.3 168.8±9.1 168.5±9.1 169.4±8.8
Physical activity, MET-h/weekb 22.3±19.8 22.5±19.9 20.9±18.4 20.7±17.5 19.3±18.0
 <7.5, % 21 20 22 23 25
 7.5-14.9, % 24 24 25 25 27
 15-29.9, % 31 31 30 30 30
 30-59.9, % 20 20 19 18 15
 ≥60, % 5 5 4 4 3
Alcohol intake, g/day 7.5±10.3 7.4±10.2 7.5±10.8 8.5±12.0 8.5±11.9
Regular aspirin use, %c 43 43 41 42 39

NHS, the Nurses’ Health Study; NHS2, the Nurses’ Health Study 2; HPFS, the Health Professionals Follow-up Study; CA, conventional adenoma; SP, serrated polyp; GRS, genetic risk score; MET, metabolic equivalent task.

a

The presented data are based on repeatedly collected information for each participant up to polyp diagnosis for cases and the end of follow-up period for non-polyps. Cumulative average values across person-endoscopies are presented. Mean±SD is presented for continuous variables and percentage for categorical variables. All variables are adjusted for age and sex except for age and sex themselves.

b

Physical activity is represented by the product sum of the METS of each specific recreational activity and hours spent on that activity per week.

c

A standard tablet contains 325 mg aspirin, and regular users were defined as those who used at least two standard tablets per week.