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.
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.
Physical activity is represented by the product sum of the METS of each specific recreational activity and hours spent on that activity per week.
A standard tablet contains 325 mg aspirin, and regular users were defined as those who used at least two standard tablets per week.