Introduction: Ankylosing spondylitis (AS) is a chronic inflammatory disease predominantly affecting the sacroiliac joints and spine. Very limited observational data regarding the long-term survival on treatment are available.
The focuses of this work were to study and to compare drug retention between the 3 anti-TNF marketed in Tunisia.
Methods: We achieved a retrospective descriptive and comparative monocentric study, on 23 patients, with AS (according to Amor criteria and ASAS 2009), during 12 years (2004-2015). The patients were treated with at least one anti-TNF, during at least 6 months. Drug survival was analysed by means of Kaplan–Meier curves.
Results: Twenty three patients were evaluated (19 men). The mean age was 40,7 years ±9,6. The median age at disease onset was 28,52±11,36 years. The mean disease duration was 9,6 (±7,17) years. Twelve patients received etanercept (ETN), 6 Infliximab (IFX) and 5 adalimumab. The median duration of prescription of anti-TNF therapy was 4,25 years [0.5-8] with 1-year and 2-year drug survival rates of 78% and 72%, respectively. No statistically significant difference in terms of survival was observed between the three anti-TNF drugs (p=0,82). The reasons for discontinuing treatment were distributed as follows: lack of efficacy in 3 cases, adverse event in 3 cases, one patient was lost from follow up. Two patients on ETN discontinued the biological drug because of paradoxical effects, and one patient on IFX discontinued the drug for urogenital tuberculosis.
Conclusion: This study demonstrated that anti-TNF showed a comparable drug retention in AS treatment. To avoid secondary effects leading to treatment discontinuation, we recommend a close monitoring.

Drug survival and causes of discontinuation of anti-TNF in ankylosing spondylitis: theTunisian experience