Characteristics of subjects in SLE group and control group
| Characteristic | SLE group (N=8310) | Control group (N=16 620) | Total | P value |
| N (%) | N (%) | N | ||
| Age, mean±SD | 37.69±14.11 | 38.34±14.95 | 1.000 | |
| 18–30 | 3039 (36.6) | 6078 (36.6) | 9117 | |
| 31–40 | 2114 (25.4) | 4228 (25.4) | 6342 | |
| 41–50 | 1628 (19.6) | 3256 (19.6) | 4884 | |
| >50 | 1529 (18.4) | 3058 (18.4) | 4587 | |
| Gender | 1.000 | |||
| Female | 7363 (88.6) | 14 726 (88.6) | 22 089 | |
| Male | 947 (11.4) | 1894 (11.4) | 2841 | |
| CCI | 1.000 | |||
| 0 | 4721 (56.8) | 9442 (56.8) | 14 163 | |
| 1 | 2151 (25.9) | 4302 (25.9) | 6453 | |
| 2 | 826 (9.9) | 1652 (9.9) | 2478 | |
| ≥3 | 612 (7.4) | 1224 (7.4) | 1836 | |
| Urbanisation | 0.767 | |||
| Urban | 5220 (62.8) | 10 370 (62.4) | 15 590 | |
| Suburban | 1100 (13.2) | 2203 (13.3) | 3303 | |
| Rural | 1990 (23.9) | 4047 (24.4) | 6037 |
CCI, Charlson Comorbidity Index; SLE, systemic lupus erythematosus.