Spondyloarthritis & psoriatic arthritis
Discriminating capacity of the ASAS health index in patients with axial spondyloarthritis treated with ixekizumab
Authors' conclusion
Several ASAS HI improvement thresholds discriminated axSpA patients in treatment vs. placebo arms at Week 16. The ASAS HI ≥30% improvement threshold discriminated across all three COAST trials.
Study context
- Population
- Patients with axial spondyloarthritis (axSpA), incl. r-axSpA (COAST-V, COAST-W) and nr-axSpA (COAST-X)
- Participants
- 587 patients3 COAST trials
- Comparison
- Ixekizumab every 4 weeks vs placebo
- Primary endpoint
- Discriminating capacity of absolute (≥2.0-≥4.0 points) and relative (≥20%-≥50%) ASAS HI improvement thresholds (threshold-based response rates IXE Q4W vs placebo)
- Follow-up
- Week 16
Methodological detailsCOAST-V, COAST-W, COAST-X, non-responder imputation, Fisher's exact test
- COAST-V, COAST-W, COAST-X
- Non-responder imputation
- Fisher's exact test
Primary result
As reported in the abstract
ASAS HI ≥30% improvement threshold, IXE Q4W vs placebo
- ASAS HI ≥30% threshold effectively discriminated treatment allocation in all trials
- IXE Q4W vs Placebo: P = 0.026
- IXE Q4W vs Placebo: P = 0.023
- IXE Q4W vs Placebo: P = 0.040
Further findings
Other ASAS HI thresholds by trial · Week 16
- COAST-W: lower absolute (≥2.0-≥3.0 points) and relative (≥20%-≥30%) thresholds discriminated effectively
- COAST-V: higher absolute (≥3.5-≥4.0 points) and relative (≥30%-≥50%) thresholds discriminated effectively
- COAST-X: ≥30%, ≥40% and ≥50% thresholds discriminated effectively
Phi coefficients, all trials and thresholds
- Phi coefficients small
- <0.3
Original publication
Discriminating capacity of the ASAS health index in patients with axial spondyloarthritis treated with ixekizumab. Semin Arthritis Rheum. Published 27 June 2025. doi:10.
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