Evaluation of the treatment effect of NSAIDs/TNF blockers according to different domains in ankylosing spondylitis: results of a meta-analysis

Objectives. To assess the treatment effect of NSAIDs and TNF blockers in AS according to different domains of interest. Methods. A systematic literature research was performed in electronic databases up to October 2009. All randomized controlled trials (RCTs) reporting the efficacy (on pain and/or physical function and/or acute-phase reactants) of NSAIDs/anti-TNF vs placebo in AS were selected. Pooled effect sizes were calculated by meta-analysis, using fixed or random-effect models. Results. Optimal data to calculate the effect size were available in 8 out of the 240 selected RCTs evaluating anti-TNF and 5 of the 135 evaluating NSAIDs. For the domains pain, physical function and patient's global assessment, the treatment effect was large or medium for both TNF blockers and NSAIDs. For the domain acute-phase reactants, the effect of TNF blockers was medium [standardized mean difference (SMD) (95% CI) -0.56 (-0.70, -0.42)], whereas NSAIDs had no significant effect on acute-phase reactants {SMD [95% odds ratio (OR)] -0.09 (-0.34, 0.16)}. Finally for the domain mobility, the effect of both TNF blockers and NSAIDs was small and not significant. Conclusion. This study suggests that the treatment effect of NSAIDs and anti-TNF are both of relevant magnitude considering the main patient-reported outcomes but with a trend in favour of anti-TNF despite the fact that such drugs are given on top of NSAIDs in refractory patients. Moreover, a statistically significant difference was observed for the domain 'acute-phase reactants' confirming the specificity of such drug category.