Is Sulfasalazine effective in ankylosing spondylitis? A systematic review of randomized controlled trials

Objective. To evaluate the efficacy and toxicity of sulfasalazine (SSZ) for the treatment of ankylosing spondylitis (AS). Methods. We searched randomized and quasi-randomized trials in any language comparing SSZ with placebo in treatment of AS. Two reviewers independently selected the studies and assessed the methodoiogical quality. Data were extracted from the chosen studies and metaanalysis was conducted with RevMan software. Results. We identified 11 trials, in which a total of 895 patients were treated for periods ranging from 12 weeks to 3 years. The pooled analysis showed that differences between SSZ and placebo were statistically significant only in erythrocyte sedimentation rate (ESR) and the severity of spinal stiffness, favoring SSZ over placebo. Weighted mean differences were ESR -4.79 mm/h (95% Cl-8.80 to -0.78) and spine stiffness -13.89 mm (95% Cl-22.54 to -5.24) on 100 mm visual analog scale (where 0 = no stiffness, 100 = severe stiffness). Nissila 1988 is the only trial in which SSZ showed benefit in primary outcome analyses, including back pain, chest expansion, occiput-to-wall test, and patient's general wellbeing. Compared with other trials, patients in this trial-had the shortest disease duration and highest level of baseline ESR, and it had the greatest proportion of patients with peripheral arthritis. Significantly more withdrawals for side effects (relative risk 1.47, 95% Cl 1.01 to 2.13) were found in the SSZ than in the placebo group, although severe side effects were rare. Conclusion. Across all patients with AS, SSZ showed some benefit in reducing ESR and easing spinal stiffness, but no evidence of benefit in physical function, pain, spinal mobility, enthesitis, or patient and physician global assessment. Patients at an early stage of disease, with higher level of ESR (or active disease) and peripheral arthritis, might benefit from SSZ.