Demographics and disease characteristics of the AS and control cohorts at start of follow-up
| AS cases (n=8600) | Controls (n=40 460) | |
|---|---|---|
| Demographics | ||
| Men; n (%) | 5637 (65.5) | 26 318 (65.0) |
| Age at the start of follow-up period; mean (SD) | 49.3 (13.9) | 48.2 (13.7) |
| Age at the first SpA diagnosis registration in the NPR; mean (SD) | 42.4 (13.4) | NA |
| Duration between the first SpA diagnosis registration in the NPR and the start of follow-up period; mean (SD) | 6.8 (8.1) | NA |
| n (%) | n (%) | |
| Foreign origin | 1012 (11.8) | 5237 (12.9) |
| Level of education >12 years | 2652 (30.8) | 12 995 (32.1) |
| Long disease duration* | 5493 (63.9) | NA |
| General comorbidities | ||
| Cardiovascular disease† | 2954 (34.4) | 8500 (21.0) |
| Hypertension | 1070 (12.4) | 1824 (4.5) |
| Ischaemic heart disease | 556 (6.5) | 1488 (3.7) |
| Congestive heart disease | 231 (2.7) | 403 (1.0) |
| Thromboembolic venous disease | 108 (1.3) | 280 (0.7) |
| Cerebrovascular disease | 263 (3.1) | 796 (2.0) |
| Other atherosclerotic disease | 249 (2.9) | 717 (1.8) |
| Other cardiovascular disease | 866 (10.1) | 1854 (4.6) |
| Cardiovascular medication | 2485 (28.9) | 7038 (17.4) |
| Diabetes mellitus† | 418 (4.9) | 1573 (3.9) |
| Diabetes mellitus type I or II | 360 (4.2) | 1131 (2.8) |
| Diabetes medication | 337 (3.9) | 1365 (3.4) |
| Infections‡ | 2826 (32.9) | 7861 (19.4) |
| Malignancy‡ | 427 (5.0) | 1532 (3.8) |
| Chronic pulmonary disease‡ | 164 (1.9) | 355 (0.9) |
| AS related clinical manifestations‡ | ||
| Anterior uveitis | 1731 (20.1) | 157 (0.4) |
| Psoriasis | 512 (6.0) | 343 (0.8) |
| Peripheral arthritis | 1841 (21.4) | 821 (2.0) |
| Inflammatory bowel disease | 644 (7.5) | 365 (0.9) |
| Aorta valve insufficiency | 79 (0.9) | 72 (0.2) |
| Joint surgery‡ | ||
| Hip replacement surgery | 432 (5.0) | 343 (0.9) |
| Other joint surgery | 213 (2.5) | 341 (0.8) |
| No of hospitalisations, median (IQR) | 2 (0–5) | 0 (0–0) |
| Pharmacological treatment at start of follow-up | ||
| NSAIDs§ | 5284 (61.4) | 3912 (9.7) |
| Oral glucocorticosteroids§ | 1224 (14.2) | 457 (1.1) |
| sDMARDs§ | 1951 (22.7) | 322 (0.8) |
| TNFi¶ | 480 (5.6) | 20 (0.05) |
| Pharmacological treatment during follow-up | ||
| NSAIDs§ | 7169 (83.4) | 19 747 (48.8) |
| Oral glucocorticosteroids§ | 2811 (32.7) | 3072 (7.6) |
| sDMARDs§ | 3244 (37.7) | 921 (2.3) |
| TNFi¶ | 1700 (19.8) | 116 (0.3) |
*If the first AS diagnosis registration in the OPR occurred before 1 January 2006.
†Based on either a visit to physician with such diagnosis (according to ICD-codes—data from the NPR) or on dispensing of pharmacological agents suggesting such diagnosis (according to Anatomical Therapeutic Chemical (ATC) codes—data from the Prescribed Drugs Register).
‡Based on a visit to physician with such diagnoses (according to ICD-codes—data from the NPR).
§Based on dispensed medication registered in the Prescribed Drugs Register according to ATC-codes.
¶Based on medication registered in the Swedish Biologics Register (ARTIS).
ARTIS, Anti-Rheumatic Therapy in Sweden Register; AS, ankylosing spondylitis; ICD, International Classification of Disease; NA, not applicable; NSAIDs, non-steroidal anti-inflammatory drugs; NPR, National Patient Register; OPR, outpatient register; sDMARDs, synthetic disease modifying antirheumatic drugs; SpA, spondyloarthritis; TNFi, tumour necrosis factor inhibitors.