Table 1.
The baseline characteristics of the study population.
| Variable | Total (N = 10965) |
Low back pain (N = 4511) |
No low back pain (N = 6810) |
P-value |
|---|---|---|---|---|
| Age (yr), mean (SD) | 50.69 ± 18.55 | 51.02 ± 18.03 | 50.49 ± 18.86 | .093* |
| Gender, N (%) | <.001 | |||
| Male | 5589 (50.97%) | 1972 (47.46%) | 3617 (53.11%) | |
| Female | 5376 (49.03%) | 2183 (52.54%) | 3193 (46.89%) | |
| Race, N (%) | <.001 | |||
| Mexican American | 2404 (21.92%) | 805 (19.37%) | 1599 (23.48%) | |
| Other Hispanic | 456 (4.16%) | 191 (4.60%) | 265 (3.89%) | |
| Non-Hispanic White | 5688 (51.87%) | 2284 (54.97%) | 3404 (49.99%) | |
| Non-Hispanic Black | 2065 (18.83%) | 753 (18.12%) | 1312 (19.27%) | |
| Other Race | 352 (3.21%) | 122 (2.94%) | 230 (3.38%) | |
| Education, N (%) | <.001 | |||
| Less than high school | 3426 (31.24%) | 1367 (32.90%) | 2059 (30.23%) | |
| High school diploma (including GED) | 2615 (23.85%) | 1075 (25.87%) | 1540 (22.61%) | |
| More than high school | 4924 (44.91%) | 1713 (41.23%) | 3211 (47.15%) | |
| PIR, N (%) | <.001 | |||
| <1.3 | 3040 (27.72%) | 1272 (30.61%) | 1768 (25.96%) | |
| ≥1.3, <3.5 | 4290 (39.12%) | 1641 (39.49%) | 2649 (38.90%) | |
| ≥3.5 | 3635 (33.15%) | 1242 (29.89%) | 2393 (35.14%) | |
| Activity, N (%) | <.001 | |||
| Not walking regularly | 2734 (24.93%) | 1141 (27.46%) | 1593 (23.39%) | |
| Do not have to carry | 5809 (52.98%) | 2098 (50.49%) | 3711 (54.49%) | |
| Climb stairs or hills often | 1673 (15.26%) | 610 (14.68%) | 1063 (15.61%) | |
| Beavy work or heavy loads | 749 (6.83%) | 306 (7.36%) | 443 (6.51%) | |
| Smoke, N (%) | <.001 | |||
| Now | 2490 (22.71%) | 1075 (25.87%) | 1415 (20.78%) | |
| Former | 2985 (27.22%) | 1170 (28.16%) | 1815 (26.65%) | |
| Never | 5490 (50.07%) | 1910 (45.97%) | 3580 (52.57%) | |
| Alcohol, N (%) | <.001 | |||
| Heavy | 2089 (19.05%) | 821 (19.76%) | 1268 (18.62%) | |
| Moderate | 1474 (13.44%) | 574 (13.81%) | 900 (13.22%) | |
| Mild | 3558 (32.45%) | 1250 (30.08%) | 2308 (33.89%) | |
| Former | 2266 (20.67%) | 924 (22.24%) | 1342 (19.71%) | |
| Never | 1578 (14.39%) | 586 (14.10%) | 992 (14.57%) | |
| Hypertension, N (%) | <.001 | |||
| Yes | 4689 (42.76%) | 1930 (46.45%) | 2759 (40.51%) | |
| No | 6276 (57.24%) | 2225 (53.55%) | 4051 (59.49%) | |
| Diabetes, N (%) | .002 | |||
| DM | 1487 (13.56%) | 626 (15.07%) | 861 (12.64%) | |
| IFG | 411 (3.75%) | 153 (3.68%) | 258 (3.79%) | |
| NO | 9067 (82.69%) | 3376 (81.25%) | 5691 (83.57%) | |
| BMI (kg/m2), mean (SD) | 28.35 ± 6.23 | 29.08 ± 6.72 | 27.90 ± 5.86 | <.001 * |
| Left leg fat (kg), mean (SD) | 4.72 ± 2.12 | 4.95 ± 2.25 | 4.57 ± 2.02 | <.001 * |
| Right leg fat (kg), mean (SD) | 4.86 ± 2.19 | 5.10 ± 2.32 | 4.71 ± 2.09 | <.001 * |
| Trunk fat (Kg), mean (SD) | 14.08 ± 6.42 | 14.89 ± 6.86 | 13.58 ± 6.09 | <.001 * |
Bold values indicate statistically significant difference at P < .05
BMI = body mass index, DM = diabetes mellitus, IFG = impaired fasting glucose, PIR = poverty income ratio, SD = standard deviation.
*
P-value: for continuous variables, the Kruskal–Wallis rank sum test was used, while for count variables with theoretical numbers <10, Fisher exact probability test was used to obtain the results.