OBJECTIVES To investigate the efficacy and safety of low-dose etanercept treatment after clinical remission of ankylosing spondylitis (AS) in the real world.

METHODS Data on 134 AS patients who were treated with etanercept for more than 12 months and achieved clinical remission (BASDAI<4 and CRP<0.5 mg/dL) were extracted from a large single centre registry. Drug survival and incidence of adverse events in 100 patients who reduced the dose during follow up (low-dose group) were compared with 34 patients who maintained the initial dose (standard-dose group). For minimisation of selection bias between the two groups, the same analyses were performed in a propensity score-matched population.

RESULTS Both groups showed similar BASDAI score and CRP levels during the follow-up. Drug survivals between the two groups were also comparable up to 4 years (vs. standard-dose group, adjusted HR=0.472, 95% CI 0.155-1.435). The same analysis performed after propensity score-matching showed concordant result. The incidence of injection site reactions in the low-dose group was significantly lower, and the incidence of other adverse events showed no differences between the two groups. In the low-dose group, dose reduction after more than 24 weeks of standard-dose treatment was associated with longer drug survival (adjusted HR=0.261, 95% CI 0.084-0.809).

CONCLUSIONS Low-dose etanercept treatment after achieving clinical remission can be an alternative treatment option in terms of its comparable long-term efficacy and favourable safety in AS. More than 24 weeks of standard-dose treatment before dose reduction may be beneficial for longer drug survival in this strategy.