Table I.
Baseline characteristics of cases and controlsa
| NHS (women) | HPFS (men) | Total | ||||
|---|---|---|---|---|---|---|
| Cases | Controls | Cases | Controls | Cases | Controls | |
| (n = 922) | (n = 1436) | (n = 587) | (n = 871) | (n = 1509) | (n = 2307) | |
| Age at diagnosis [years, mean (SD)] | 66.8 (9.2) | 69.2 (9.2) | 67.7 (9.3) | |||
| Age at sample draw (years, mean) | 59.5 (6.6) | 59.6 (6.5) | 64.8 (8.5) | 64.9 (8.4) | 62.5 (8.2) | 62.1 (7.9) |
| Non-white (%) | 13 (1.4) | 6 (0.4) | 49 (8.4) | 59 (6.8) | 62 (4.1) | 65 (2.5) |
| Regular aspirin use (%)b | 324 (35.1) | 656 (45.7) | 269 (45.8) | 450 (51.7) | 593 (39.3) | 1106 (47.9) |
| Regular NSAID drug use (%)c | 303 (32.9) | 570 (39.7) | 136 (23.2) | 190 (21.8) | 439 (29.1) | 760 (32.9) |
| BMI [kg/m2, mean (SD)]d | 26.1 (5.1) | 26.0 (5.0) | 26.2 (3.3) | 25.6 (3.3) | 26.1 (4.5) | 25.8 (4.5) |
| Physical activity [METs - h/week, mean (SD)]e | 15.7 (14.3) | 16.0 (14.0) | 29.4 (24.2) | 31.1 (25.2) | 21.1 (20.0) | 21.8 (20.5) |
| CRC in a parent or sibling (%) | 212 (23.0) | 239 (16.6) | 114 (19.4) | 132 (15.2) | 326 (21.6) | 371 (16.1) |
| Former or current smoker (%) | 537 (59.0) | 791 (55.0) | 319 (60.0) | 441 (55.0) | 856 (59.0) | 1232 (55.0) |
| Alcohol consumption [g/day, mean (SD)] | 6.8 (10.2) | 6.3 (9.4) | 13.4 (15.7) | 11.8 (13.2) | 9.4 (13.1) | 8.4 (11.3) |
| Beef, pork or lamb as a main dish [servings/week, mean (SD)] | 2.8 (0.8) | 2.8 (0.8) | 2.7 (0.9) | 2.6 (0.9) | 2.7 (0.8) | 2.7 (0.8) |
| Total calcium intake (mg/day, mean)f | 952.4 (364.1) | 1007.5 (386.9) | 916.1 (399.4) | 950.6 (382.5) | 938.1 (378.7) | 985.8 (386.2) |
| Total folate intake (µg/day, mean)f | 426.8 (179.1) | 447.8 (194.9) | 526.0 (226.2) | 566.2 (231.6) | 465.9 (204.7) | 492.9 (217.3) |
aAt blood draw or cheek cell sampling.
bRegular aspirin user was defined as the consumption of at least two 325mg tablets per week in the NHS and at least two times per week in the HPFS. Non-regular user was defined otherwise.
cRegular NSAID user was defined as the consumption of NSAIDs at least two times per week. Non-regular user was defined otherwise.
dThe BMI is the weight in kilograms divided by the square of the height in meters.
eMetabolic Equivalent of Task (MET) denotes metabolic equivalent. Met (h) = sum of the average time/week in each activity × MET value of each activity. One MET, the energy spent sitting quietly, is equal to 3.5ml of oxygen uptake per kilograms of body weight per minute for a 70kg adult.
fNutrient values (calcium and folate) represent the mean of energy-adjusted intakes.