Table 1 Baseline characteristics of the enrolled participants by vitamin D status
Variables |  | Total (n = 2661) | Vitamin D < 20 ng/ml (n = 1677) | Vitamin D 20 - 29ng/ml (n = 846) | Vitamin D ≥ 30ng/ml (n = 138) | P-value |
|---|---|---|---|---|---|---|
Age (years) |  | 67.7 ± 6.0 | 67.8 ± 6.0 | 67.0 ± 5.7 | 67.6 ± 6.5 | < 0.001 |
Gender | ||||||
 Males (n, %) |  | 1090 (41.0) | 526 (31.4) | 472 (55.8) | 92 (66.7) | < 0.001 |
 Females (n, %) |  | 1571 (59.0) | 1151 (68.6) | 374 (44.2) | 46 (33.3) |  |
Ethnics (n, %) | Han | 1146 (43.1) | 641 (38.2) | 426 (50.4) | 79 (57.2) | < 0.001 |
Zang | 633 (23.8) | 452 (27.0) | 152 (18.0) | 29 (21) | Â | |
Qiang | 696 (26.2) | 482 (28.7) | 190 (22.5) | 24 (17.4) | Â | |
Others | 186 (7.0) | 102 (6.1) | 78 (9.2) | 6 (4.3) | Â | |
Smoking history (n, %) | Yes | 484 (19.2) | 237 (15.0) | 210 (26.0) | 37 (27.8) | < 0.001 |
Drinking history (n, %) | Yes | 677 (26.9) | 379 (24.0) | 250 (31.0) | 48 (36.1) | < 0.001 |
Educational level (n, %) | Illiteracy | 936 (35.2) | 648 (38.6) | 255 (30.1) | 33 (23.9) | < 0.001 |
Primary school | 1338 (50.3) | 788 (47.0) | 465 (55.0) | 85 (61.6) | Â | |
High or secondary school | 208 (7.8) | 123 (7.3) | 71 (8.4) | 14 (10.1) | Â | |
Graduate or above | 179 (6.7) | 118 (7.0) | 55 (6.5) | 6 (4.3) | Â | |
Marital status (n, %) | Single | 649 (24.4) | 464 (27.7) | 158 (18.7) | 27 (19.6) | < 0.001 |
Altitude (n, %) | 0 - 999 | 394 (14.8) | 171 (10.2) | 176 (20.8) | 47 (34.1) | < 0.001 |
1000 - 999 | 1319 (49.6) | 860 (21.3) | 416 (49.2) | 43 (31.2) | Â | |
≥ 2000 | 948 (35.6) | 646 (38.5) | 254 (30.0) | 48 (34.8) |  | |
Number of chronic diseases (n, %) | 0 | 1383 (52.0) | 74 (48.1) | 1235 (52.1) | 74 (53.6) | 0.444 |
1 | 613 (23.0) | 32 (20.8) | 552 (23.3) | 29 (21.0) | Â | |
≥ 2 | 665 (25.0) | 48 (31.2) | 582 (24.6) | 35 (25.4) |  | |
Physical activity | Regular physical activity | 1893 (75.2) | 108 (76.1) | 1673 (74.6) | 112 (84.2) | 0.043 |
Less physical activity | 625 (24.8) | 34 (23.9) | 570 (25.4) | 21 (15.8) | Â | |