Table 2.
Characteristics of the axSpA patients from the ASAS-PerSpA study analysed in this study, stratified by age at onset
| Characteristics | Total (N = 2579) | Age at onset <45 years (n = 2368) | Age at onset ≥45 years (n = 211) |
|---|---|---|---|
| Gender, male, % | 69 | 70 | 51 |
| Age, years, median (IQR) | 40 (31–51) | 39 (31–48) | 58 (53–64) |
| Symptom duration, years, median (IQR) | 11 (5–19) | 11 (5–20) | 6 (3–11) |
| HLA-B27 positive, % | 79** | 80** | 60*** |
| IBP ASAS definitiona, % | 94 | 95 | 87 |
| Positive family history, % | 34 | 35 | 25 |
| Peripheral arthritis, % | 44 | 43 | 50 |
| Enthesitis, % | 45 | 45 | 49 |
| Dactylitis, % | 6 | 6 | 7 |
| Psoriasis, % | 8 | 8 | 10 |
| IBD, % | 5 | 5 | 7 |
| Acute anterior uveitis, % | 22 | 23 | 17 |
| Elevated CRP, % | 70 | 71 | 61 |
| Sacroiliitis on pelvic radiographsb, % | 78 | 79 | 68 |
| Sacroiliitis on pelvic MRIb, % | 82*** | 83*** | 76*** |
| SpA featuresc, mean (s.d.) | 4 (2) | 4 (2) | 4 (2) |
| Use of bDMARD, % | 33* | 33* | 30* |
| Use of NSAID, % | 99* | 99* | 97* |
| r-axSpA, % | 79 | 80 | 73 |
| LOC regarding axSpA diagnosis, mean (s.d.) | 8 (3) | 8 (3) | 7 (3) |
a
Four of five of the following features: onset before the age of 40 years, insidious onset, improvement with exercise, no improvement with rest, pain at night [21]. bBased on reading of local radiologists. cExcluding HLA-B27 status and sacroiliitis on imaging. *5–10% missing values **10–20% missing values ***20–40% missing values. bDMARD: biologic DMARD; LOC: level of confidence regarding the diagnosis.