| Subgroup | Thrombotic events | Rate of events/1,000 person-years | Rate ratios (95% CI) | P value |
---|---|---|---|---|---|
Current prednisone | None | 52 | 10.6 | 1.0 (Ref. Gp) | Â |
 | 1 to 9 mg/day | 40 | 16.4 | 1.6 (1.1 to 2.4) | 0.025 |
 | 10 to 19 mg/day | 49 | 34.3 | 3.3 (2.2 to 4.8) | <0.0001 |
 | 20+ mg/day | 43 | 71.8 | 6.5(4.3 to 9.8) | <0.0001 |
Cumulative prednisone dose | None | 29 | 13.1 | 1.0 (Ref. Gp) | Â |
 | <1 year (10 mg/day) | 37 | 23.8 | 1.6 (1.0 to 2.6) | 0.075 |
 | 1 to 3 years (10 mg/day) | 30 | 19.0 | 1.8 (1.1 to 3.1) | 0.026 |
 | 3 to 10 years (10 mg/day) | 45 | 25.5 | 3.0 (1.8 to 5.2) | <0.0001 |
 | >10 years (10 mg/day) | 9 | 24.3 | 3.7 (1.5 to 9.4) | 0.0056 |
Current HCQ | No | 95 | 29.0 | 1.0 (Ref. Gp) | Â |
 | Yes | 90 | 14.6 | 0.5 (0.4 to 0.7) | <0.0001 |
HCQ use | Never | 57 | 32.2 | 1.0 (Ref. Gp) | Â |
 | Past (not current) | 27 | 27.6 | 0.9 (0.6 to 1.5) | 0.81 |
 | <6 consecutive months | 16 | 20.0 | 0.6 (0.3 to 1.0) | 0.056 |
 | >6 consecutive months | 64 | 13.8 | 0.5 (0.3 to 0.7) | 0.0003 |
NSAID use | No | 146 | 21.6 | 1.0 (Ref. Gp) | Â |
 | Yes | 37 | 13.9 | 0.6 (0.4 to 0.9) | 0.017 |
Aspirin use | No | 137 | 17.9 | 1.0 (Ref. Gp) | Â |
 | Yes | 49 | 28.0 | 1.6 (1.2 to 2.3) | 0.0038 |