Table 1.
Baseline characteristics among study groups.
| Before PSM (1:4 age–sex matching) | After 1:2 PSM | |||||
|---|---|---|---|---|---|---|
| Non-AS n = 24,012 | ASn= 6,003 | ASD | Non-ASn = 11,392 | AS n = 5,696 | ASD | |
| Sex | 0.000 | 0.027 | ||||
| Female | 10,024 (41.75%) | 2,506 (41.75%) | 4,689 (41.16%) | 2,330 (40.91%) | ||
| Male | 13,988 (58.25%) | 3,497 (58.25%) | 6,703 (58.84%) | 3,366 (59.09%) | ||
| Age | 0.004 | 0.008 | ||||
| <30 | 6,305 (26.26%) | 1,566 (26.09%) | 2,980 (26.16%) | 1,511 (26.53%) | ||
| 30–45 | 6,931 (28.86%) | 1,754 (29.22%) | 3,267 (28.68%) | 1,666 (29.25%) | ||
| 45–65 | 6,983 (29.08%) | 1,734 (28.89%) | 3,274 (28.74%) | 1,609 (28.25%) | ||
| ≥65 | 3,793 (15.80%) | 949 (15.81%) | 1,871 (16.42%) | 910 (15.98%) | ||
| Urbanization | 0.076 | 0.022 | ||||
| Urban | 14,542 (60.56%) | 3,509 (58.45%) | 6,534 (57.36%) | 3,319 (58.27%) | ||
| Sub-urban | 7,182 (29.91%) | 1,870 (31.15%) | 3,650 (32.04%) | 1,783 (31.30%) | ||
| Rural | 2,288 (9.53%) | 624 (10.39%) | 1,208 (10.60%) | 594 (10.43%) | ||
| Low income | 145 (0.60%) | 24 (0.40%) | 0.029 | 47 (0.41%) | 24 (0.42%) | 0.001 |
| Length of hospital stays† | 0.136 | 0.000 | ||||
| 0 day | 22,146 (92.23%) | 5,292 (88.16%) | 10,114 (88.78%) | 5,042 (88.52%) | ||
| 1–6 days | 1,082 (4.51%) | 4,35 (7.25%) | 757 (6.65%) | 402 (7.06%) | ||
| ≥7 days | 784 (3.27%) | 276 (4.60%) | 521 (4.57%) | 252 (4.42%) | ||
| Co-morbidity† | ||||||
| RA | 127 (0.53%) | 299 (4.98%) | 0.275 | 5 (0.04%) | 3 (0.05%) | 0.004 |
| Hypertension | 3,450 (14.37%) | 1,160 (19.32%) | 0.133 | 2,090 (18.35%) | 1,097 (19.26%) | 0.023 |
| Diabetes mellitus | 1,604 (6.68%) | 518 (8.63%) | 0.073 | 9,66 (8.48%) | 493 (8.66%) | 0.006 |
| Hyperlipidemia | 1,777 (7.40%) | 638 (10.63%) | 0.113 | 1,101 (9.66%) | 596 (10.46%) | 0.027 |
| CKD | 188 (0.78%) | 60 (1.00%) | 0.023 | 108 (0.95%) | 55 (0.97%) | 0.002 |
| COPD | 1,202 (5.01%) | 416 (6.93%) | 0.081 | 759 (6.66%) | 391 (6.86%) | 0.008 |
| Chronic liver diseases | 1,049 (4.37%) | 439 (7.31%) | 0.126 | 703 (6.17%) | 412 (7.23%) | 0.042 |
| Gout | 935 (3.89%) | 506 (8.43%) | 0.189 | 708 (6.21%) | 440 (7.72%) | 0.059 |
| Depression | 1,571 (6.54%) | 727 (12.11%) | 0.192 | 1,124 (9.87%) | 672 (11.80%) | 0.062 |
| Medication† | ||||||
| Systemic corticosteroids | 4,913 (20.46%) | 2,339 (38.96%) | 0.413 | 3,850 (33.80%) | 2,145 (37.66%) | 0.081 |
| NSIADs | 14,298 (59.55%) | 5,874 (97.85%) | 1.059 | 11,135 (97.74%) | 5,567 (97.74%) | 0.001 |
| Hydroxychloroquine | 50 (0.21%) | 169 (2.82%) | 0.215 | 21 (0.18%) | 102 (1.79%) | 0.163 |
| Methotrexate | 34 (0.14%) | 107 (1.78%) | 0.169 | 13 (0.11%) | 63 (1.11%) | 0.128 |
| Sulfasalazine | 30 (0.12%) | 1,172 (19.52%) | 0.689 | 7 (0.06%) | 1,027 (18.03%) | 0.660 |
†
The length of hospital stays, co-morbidity, use of medications were identified within 1 year before index date.