Patient demographics and classification information.
| Native American n=268 | African-American n=1074 | European American n=1567 | Hispanic n=239 | |
| Females, n (%) | 233 (87) | 985 (92) | 1387 (89) | 214 (90) |
| Country of residence, n (%) | ||||
| USA/Puerto Rico, n (%) | 190 (71) | 1071 (99.7) | 1542 (98.4) | 239 (100) |
| Canada, n (%) | 1 (0.3) | 0 | 25 (1.63) | 0 |
| Latin America (Colombia/British Virgin Islands/Barbados), n (%) | 72 (27) | 3 (0.3) | 0 | 0 |
| Undisclosed, n (%) | 5 (2) | 0 | 0 | 0 |
| Age of disease classification, mean±SD | 29.89±12.3 | 30.83±11.19 P=0.1230 | 32.02±12.87 P=0.0157 | 27.77±11.66 P=0.0867 |
| Age at collection, mean±SD | 39.5±13.32 | 41.43±12.53 P=0.0323 | 43.88±13.42 P<0.0001 | 38.27±12.43 P=0.2850 |
| No. of ACR criteria met, mean±SD | 5.179±1.238 | 5.202±1.306 P=0.9384 | 5.154±1.233 P=0.6823 | 5.347±1.409 P=0.3113 |
Demographics were collected by patient report. ACR classification criteria were extracted by standardised, protocol-directed medical record extraction for all individuals. Age of disease onset, age at collection and average ACR criteria met were analysed using non-parametric, unpaired Mann-Whitney test. Bold P values are significant compared with the Native American group.
ACR, American College of Rheumatology.