Background: Axial spondyloarthritis (axSpA) is characterized by progressive structural damage. Early biologic therapy has been proposed to modify long-term outcomes, but the magnitude of benefit remains unclear.

Objectives: To quantify the impact of early (<2 years from symptom onset) versus delayed biologic therapy on radiographic progression in axSpA.

Methods: A systematic literature search was conducted in MEDLINE, Embase, and CENTRAL through January 2025. Eligible studies included RCT extensions and observational cohorts reporting radiographic outcomes using the modified Stoke Ankylosing Spondylitis Spinal Score (mSASSS). Random-effects meta-analysis was performed, and subgroup analyses compared early vs. delayed initiation. Risk of bias was assessed using ROBINS-I and RoB2.

Results: Eighteen studies (n = 12,901) were included: 6 RCT extensions and 12 prospective cohorts. Patients receiving early biologic therapy demonstrated significantly lower radiographic progression over 2–4 years (mean ΔmSASSS = 0.81 units/year , 95% CI 0.65–0.97) compared with delayed therapy ( 1.30 units/year , 95% CI 1.12–1.55). Pooled standardized mean difference favored early treatment (SMD = −0.42 , 95% CI −0.56 to −0.27). The relative risk of high progression (≥2 mSASSS units/year) was reduced by 38% (RR 0.62, 95% CI 0.51–0.75). Subgroup analysis showed the greatest benefit in non-radiographic axSpA (SMD = −0.51). Heterogeneity was low to moderate (I ² = 28%). No differences in serious adverse events were identified (RR 0.98, 95% CI 0.87–1.12).

Conclusions: Early initiation of biologic therapy is associated with significantly reduced radiographic progression compared with delayed treatment in axSpA. Benefits were observed across disease stages, with the strongest effect in early/non-radiographic disease. These findings support early aggressive treatment strategies to prevent irreversible structural damage.

REFERENCES: NIL.

Acknowledgments: NIL.

Disclosure of Interests: None declared.