Participant characteristics, National Health and Nutrition Examination Survey 2007–1016
| Variable | Overall | No rheumatoid arthritis | Rheumatoid arthritis | P value |
| Statistics | Statistics | Statistics | ||
| Unweighted, N | 21 987 | 20 569 | 1418 | |
| Weighted, N | 175 972 927 | 167 283 731 | 8 689 197 | |
| Female, % (95% CI) | 49.5 (48.9 to 50.2) | 48.9 (48.2 to 49.6) | 61.8 (58.1 to 65.4) | <0.001* |
| Age at screening (years), mean (95% CI) | 43.8 (43.3 to 44.3) | 43.1 (42.6 to 43.6) | 57.7 (56.9 to 58.6) | <0.001† |
| Race, % (95% CI) | ||||
| Non-Hispanic white | 63.4 (60.0 to 66.8) | 63.3 (59.8 to 66.7) | 66.0 (61.5 to 70.4) | <0.001* |
| Non-Hispanic black | 12.0 (10.4 to 13.8) | 11.7 (10.1 to 13.5) | 17.1 (13.9 to 20.7) | |
| Mexican-American | 9.8 (8.0 to 11.8) | 9.9 (8.1 to 11.9) | 7.4 (5.5 to 9.8) | |
| Other | 14.8 (13.2 to 16.4) | 15.1 (13.5 to 16.7) | 9.4 (7.4 to 11.7) | |
| Education level, % (95% CI)‡ | ||||
| Less than high school | 16.7 (15.3 to 18.1) | 16.2 (14.8 to 17.6) | 25.6 (22.6 to 28.8) | <0.001* |
| High school/GED/some college/AA | 53.1 (51.6 to 54.7) | 52.8 (51.2 to 54.3) | 59.9 (56.2 to 63.6) | |
| College graduate+ | 30.2 (28.1 to 32.3) | 31.0 (28.9 to 33.2) | 14.5 (11.5 to 17.9) | |
| Health insurance, % (95% CI)‡ | ||||
| None | 20.8 (19.6 to 22.1) | 21.3 (20.0 to 22.7) | 11.4 (9.1 to 14.0) | <0.001* |
| Private | 62.1 (60.3 to 63.9) | 62.7 (60.8 to 64.6) | 49.9 (45.8 to 54.0) | |
| Other | 17.1 (16.0 to 18.2) | 16.0 (14.9 to 17.0) | 38.7 (35.0 to 42.5) | |
| Marital status, % (95% CI) | ||||
| Married/widowed | 57.9 (56.4 to 59.4) | 57.5 (56.0 to 59.1) | 65.3 (62.2 to 68.3) | <0.001* |
| Separated/divorced | 11.9 (11.2 to 12.6) | 11.5 (10.8 to 12.2) | 19.5 (17.0 to 22.1) | |
| Never married/living with partner | 30.2 (28.6 to 31.9) | 31.0 (29.3 to 32.7) | 15.2 (12.9 to 17.8) | |
| Family PIR, mean (95% CI)‡ | 2.9 (2.9 to 3.0) | 3.0 (2.9 to 3.1) | 2.4 (2.3 to 2.6) | <0.001† |
| Annual household income, % (95% CI)‡ | ||||
| Under $55 000 | 48.7 (46.3 to 51.0) | 47.7 (45.4 to 50.1) | 66.6 (62.1 to 70.9) | <0.001* |
| $55 000–$99 999 | 25.5 (24.1 to 26.9) | 25.7 (24.3 to 27.1) | 22.2 (18.6 to 26.2) | |
| $100 000 and up | 25.9 (23.5 to 28.3) | 26.6 (24.3 to 29.1) | 11.2 (8.4 to 14.5) | |
| Body mass index (kg/m2), mean (95% CI) | 28.4 (28.3 to 28.6) | 28.3 (28.1 to 28.5) | 30.9 (30.4 to 31.5) | <0.001† |
| Smoking status, % (95% CI)‡ | ||||
| Never | 58.0 (56.7 to 59.4) | 58.8 (57.4 to 60.1) | 44.2 (40.4 to 48.0) | <0.001* |
| Past | 21.4 (20.4 to 22.5) | 20.9 (19.9 to 22.0) | 30.4 (26.8 to 34.2) | |
| Current | 20.6 (19.6 to 21.6) | 20.3 (19.3 to 21.3) | 25.4 (21.9 to 29.3) | |
| Dietary fibre (gm), mean (95% CI)‡ | 17.3 (17.1 to 17.6) | 17.4 (17.1 to 17.7) | 15.5 (14.7 to 16.2) | <0.001† |
| HEI-2015 score, mean (95% CI) | 50.9 (50.5 to 51.3) | 51.0 (50.5 to 51.4) | 50.3 (49.1 to 51.5) | 0.30† |
| PHQ-9 depression severity, % (95% CI)‡ | ||||
| None to mild, 0–9 | 93.3 (92.8 to 93.8) | 93.8 (93.3 to 94.3) | 83.2 (80.2 to 85.9) | <0.001* |
| Moderate to severe, 10+ | 6.7 (6.2 to 7.2) | 6.2 (5.7 to 6.7) | 16.8 (14.1 to 19.8) | |
| Any vigorous or moderate activities, % (95% CI)‡ | 73.8 (72.7 to 74.9) | 74.6 (73.5 to 75.7) | 58.2 (54.7 to 61.7) | <0.001* |
| Creatinine, urine (mg/dL), mean (95% CI)‡ | 123.3 (121.0 to 125.5) | 123.7 (121.4 to 126.0) | 115.1 (109.5 to 120.8) | 0.004* |
Bold indicates the significant with p<0.05.
*Rao-Scott χ2 test.
†linear regression. MEC weights and SAS SURVEY procedures used for all analyses.
‡Data not available for all subjects. Education level=23; health insurance=22; served in U.S. armed forces=1; marital status=11; family poverty income ratio=1998; annual household income=2020; body mass index (kg/m2)=260; smoking status=17; PHQ-9 depression severity=2453; vigorous or moderate activities=9; dietary fibre (gm)=1703; creatinine, urine (mg/dL)=472.
HEI-2015, Healthy Eating Index; PHQ-9, Patient Health Questionnaire-9; PIR, poverty income ratio.