Table 1.
Characteristics of Participants Who Provided Cold and Influenza-like Illness Data
| Characteristic | Participants, No. (%) |
||||
|---|---|---|---|---|---|
| Polyp Prevention Studya |
Colds and Flu Substudyb |
||||
| Vitamin D | Placebo | Vitamin D | Placebo | ||
| n = 1130 | n = 1129 | n = 399 | n = 360 | P Valuec | |
| Age at enrollment, y, mean (SD) | 58.1 (6.9) | 58.0 (6.8) | 57.9 (6.7) | 57.8 (6.3) | .89 |
| Age as of 1 November 2009, mean (SD) | 61.5 (7.0) | 61.3 (6.9) | 60.7 (6.7) | 60.5 (6.4) | .78 |
| Male sex | 712 (63.0) | 711 (63.0) | 237 (59.4) | 201 (55.8) | .32 |
| Race | .22 | ||||
| White | 951 (88.1) | 949 (87.8) | 352 (90.5) | 309 (88.8) | |
| Black | 96 (8.9) | 88 (8.1) | 27 (6.9) | 26 (7.5) | |
| Asian | 25 (2.3) | 26 (2.4) | 9 (2.3) | 7 (2.0) | |
| Other | 7 (28.0) | 18 (1.7) | 1 (0.3) | 6 (1.7) | |
| Missing | 51 | 48 | 10 | 12 | |
| Hispanic ethnicity | 76 (6.7) | 70 (6.2) | 20 (5.0) | 22 (6.1) | .50 |
| Missing | 1 | 2 | 0 | 1 | |
| Body mass index at enrollment, kg/m2 | |||||
| Mean | 28.9 (5.0) | 29.1 (5.3) | 28.6 (5.2) | 28.6 (5.4) | |
| <25.0 | 272 (24.1) | 245 (21.7) | 112 (28.1) | 94 (26.2) | |
| 25.0–29.9 | 458 (40.6) | 458 (40.6) | 159 (40.0) | 147 (41.0) | |
| 30.0–34.9 | 266 (23.6) | 288 (25.6) | 82 (20.6) | 81 (22.6) | |
| ≥35.0 | 133 (11.8) | 136 (12.1) | 45 (11.3) | 37 (10.3) | |
| Missing | 1 | 2 | 1 | 1 | |
| Smoking status at enrollment | .70 | ||||
| Never | 590 (52.2) | 604 (53.5) | 228 (57.1) | 201 (55.8) | |
| Former | 421 (37.3) | 429 (38.0) | 141 (35.3) | 136 (37.8) | |
| Current | 119 (10.5) | 96 (8.5) | 30 (7.5) | 23 (6.4) | |
| Pretrial supplements | |||||
| Multivitamin | 633 (56.0) | 634 (56.3) | 222 (55.6) | 222 (61.8) | .08 |
| Vitamin D | 158 (14.0) | 137 (12.2) | 66 (16.5) | 66 (18.4) | .50 |
| Vitamin C | 219 (19.4) | 271 (24.0) | 66 (16.6) | 82 (22.8) | .03 |
| Zinc | 49 (4.3) | 38 (3.4) | 16 (4.0) | 11 (3.1) | .48 |
| Serum 25(OH)D at enrollment, ng/mL | |||||
| Mean | 24.6 (8.2) | 24.5 (8.5) | 24.8 (8.3) | 25.3 (8.8) | .39 |
| <20 | 380 (33.6) | 402 (35.6) | 127 (31.8) | 112 (31.1) | |
| 20–29.9 | 474 (42.0) | 452 (40.0) | 167 (41.9) | 151 (41.9) | |
| ≥30 | 276 (24.4) | 275 (24.4) | 105 (26.3) | 97 (26.9) | |
| Serum 25(OH)D, ng/mLd | |||||
| Mean | 31.8 (9.9) | 23.9 (8.9) | 33.3 (9.9) | 25.1 (9.1) | <.0001 |
| <20 | 108 (9.9) | 429 (39.0) | 25 (6.3) | 122 (33.9) | |
| 20–29.9 | 413 (37.7) | 431 (39.2) | 143 (35.9) | 136 (37.8) | |
| ≥30 | 575 (52.5) | 239 (21.8) | 230 (57.8) | 102 (28.3) | |
| Missing | 34 | 30 | 1 | 0 | |
Abbreviations: 25(OH)D, 25-hydroxyvitamin D; SD, standard deviation.
a These participants provided symptom data by telephone every 6 months from 2007 to 2012.
b These participants also provided symptom data via daily health diaries from 2009 to 2011.
c P values are shown for comparisons in the Colds and Flu (CAF) substudy participants.
d The blood draw closest in time to the start of participation in the CAF substudy.