Clinical Features of Late-onset Ankylosing Spondylitis: Comparison with Early-onset Disease
Bibliographic record
Abstract
OBJECTIVE: Ankylosing spondylitis (AS) is generally observed in young patients but can occur later in life or in persons ≥ 50 years of age. Our objective was to characterize the clinical features of late-onset AS in a large multicenter national cohort. METHODS: We studied late-onset AS in the National Registry of Spondyloarthritis of the Spanish Society of Rheumatology (REGISPONSER database) cohort (n = 1257), of whom 3.5% had onset at age ≥ 50 years versus a control group with onset at < 50 years. RESULTS: There were no differences between late-onset and early-onset AS according to sex and family history of spondyloarthropathies. Patients in the late-onset group more often showed involvement of the cervical spine (22.7% vs 9.7%; p = 0.03) and arthritis of the upper (13.6% vs 3.0%; p = 0.002) and lower limbs (27.3% vs 15.2%; p = 0.03) as first manifestations than did patients in the early-onset group. A higher percentage of mixed forms (axial and peripheral joint disease) during the course of the disease was also recorded in the late-onset group (50% vs 24%; p = 0.0001). CONCLUSION: Our study suggests that age at onset of AS affects the patients' presenting clinical form. Arthritis of the upper limbs requires a differential diagnosis with other conditions frequent in patients over 50 years of age, such as rheumatoid arthritis or crystal-induced arthropathy.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".