Characteristics of patients with AS and matched controls at index date
| Characteristic | Patients with AS (%) | Controls (%) |
|---|---|---|
| N=4101 | N=28 591 | |
| Male | 2897 (70.6) | 20 173 (70.6) |
| Age at index date (years) | ||
| 16–29 | 773 (18.8) | 5407 (18.9) |
| 30–39 | 1115 (27.2) | 7781 (27.2) |
| 40–49 | 887 (21.6) | 6203 (21.7) |
| 50–59 | 618 (15.1) | 4314 (15.1) |
| 60+ | 708 (17.3) | 4886 (17.1) |
| Smoking | ||
| Current | 1489 (36.3) | 9022 (31.6)* |
| Ex | 616 (15.0) | 3966 (13.9)* |
| Never | 1825 (44.5) | 13 081 (45.5) |
| Unknown | 171 (4.2) | 2522 (8.8)* |
| Alcohol | ||
| Yes | 2817 (68.7) | 19 118 (66.9)* |
| No | 647 (15.8) | 3588 (12.5)* |
| Unknown | 637 (15.5) | 5885 (20.6)* |
| BMI | ||
| <20 | 220 (5.4) | 1386 (4.8) |
| 20–25 | 1123 (27.4) | 7612 (26.6) |
| 25–30 | 939 (22.9) | 6664 (23.3) |
| >30 | 500 (12.2) | 3409 (11.9) |
| Unknown | 1319 (32.2) | 9520 (33.3) |
| Medication 6 months before index date | ||
| NSAID | 1923 (46.9) | 2460 (8.6)* |
| History of EAM before index date | ||
| AAU | 466 (11.4) | 143 (0.5)* |
| Psoriasis | 182 (4.4) | 749 (2.6)* |
| IBD | 151 (3.7) | 176 (0.6)* |
*Statistically significant difference (p<0.05) between patients with AS and controls, based on χ2 test.
AAU, acute anterior uveitis; AS, ankylosing spondylitis; BMI, body mass index; EAM, extra-articular manifestation; IBD, inflammatory bowel disease; NSAID, non-steroidal anti-inflammatory drug.