Table 1.
Baseline characteristics of study participants by quartile intake of dietary total fiber
| Quartile (Q) of dietary total fiber | Q1 (Lowest) (N=2,239) | Q2 (N=2,231) | Q3 (N=2,236) | Q4 (Highest) (N=2,234) |
|---|---|---|---|---|
| Age (years) at baseline, mean (SD) | 59.7 (9.0) | 60.9 (9.1) | 61.8 (9.1) | 62.7 (9.1) |
| Caucasian, n (%) | 1753 (78.3) | 1863 (83.5) | 1827 (81.7) | 1794 (80.3) |
| Women, n (%) | 1301 (58.1) | 1296 (58.1) | 1286 (57.5) | 1296 (58.0) |
| BMI (kg/m2) | ||||
| At baseline | 29.4 (5.0) | 28.8 (4.7) | 28.6 (4.7) | 27.6 (4.4) |
| At 96-month exam | 29.7 (5.6) | 28.8 (5.1) | 28.5 (4.8) | 27.8 (4.7) |
| Tobacco use, n (%) | ||||
| Never | 1782 (79.6) | 1763 (79.0) | 1726 (77.2) | 1785 (79.9) |
| Former | 368 (16.5) | 384 (17.2) | 434 (19.4) | 389 (17.4) |
| Current | 89 (4.0) | 84 (3.8) | 76 (3.4) | 60 (2.7) |
| Education, n (%) | ||||
| less than college level | 1041 (46.5) | 895 (40.1) | 827 (37.0) | 753 (33.7) |
| college level or above | 1798 (53.5) | 1336 (59.9) | 1409 (63.0) | 1481 (66.3) |
| Physical Activity Scale for Elderly | 156.1 (80.9) | 160.0 (81.7) | 163.2 (79.9) | 166.4 (84.1) |
| Usage of NSAIDs (%) | 616 (27.5) | 580 (26.0) | 523 (23.4) | 500 (22.4) |
| Kellgren-Lawrence grade, n (%) | ||||
| 0-1 | 1187 (53.0) | 1248 (55.9) | 1263 (56.4) | 1300 (58.2) |
| 2-4 | 1052 (47.0) | 983 (44.1) | 973 (43.6) | 934 (41.8) |
| WOMAC pain score (range 0-20) | ||||
| Baseline | 2.75 (3.58) | 2.29 (3.02) | 2.26 (3.14) | 2.08 (3.02) |
| 12-month | 2.55 (3.65) | 2.06 (3.04) | 2.09 (3.06) | 1.78 (2.76) |
| Depression, n (%) | ||||
| CES-D <16 | 1917 (85.6) | 2021 (90.6) | 2046 (91.5) | 2069 (92.6) |
| CES-D ≥16 | 322 (14.4) | 210 (9.4) | 190 (8.5) | 165 (7.4) |
| Total energy, kcal/day, median (IQR) | 1333.5 (974.9,1728.5) | 1354.1 (1044.2, 1734.0) | 1314.0 (1008.3, 1691.9) | 1287.3 (978.3, 1640.1) |
| Total dietary fiber, g/day, median (IQR) | 8.6 (6.3, 11.3) | 12.5 (9.9, 15.6) | 15.2 (12.2, 19.0) | 20.6 (16.2, 26.5) |
| Grain fiber, g/day, median (IQR) | 3.7 (2.5, 5.2) | 5.0 (3.5, 6.8) | 5.7 (3.9, 8.0) | 6.8 (4.5, 9.8) |
| Fruit and vegetable fiber, g/day, median (IQR) | 3.8 (2.6, 5.4) | 6.1 (4.5, 8.1) | 7.8 (6.0, 10.0) | 10.5 (7.8, 14.0) |
| Nut and legume fiber, g/day, median (IQR) | 0.8 (0.4, 1.4) | 1.4 (0.8, 2.1) | 1.6 (1.0, 2.6) | 2.3 (1.2, 4.0) |
NSAIDs: nonsteroidal anti-inflammatory drug;
CES-D: Center for Epidemiologic Studies Depression Scale;
IQR: interquartile range.
All differences among quartiles of total fiber intake were statistically significant at p<0.01, except sex distribution (p=0.98) and tobacco use (p=0.056).