Summary of findings for the main comparison. Sulfasalazine compared to placebo for ankylosing spondylitis.
| Sulfasalazine compared to placebo for ankylosing spondylitis | ||||||
| Patient or population: Patients with ankylosing spondylitis Settings: Outpatients and inpatients Intervention: Sulfasalazine Comparison: Placebo | ||||||
| Outcomes | Illustrative comparative risks* (95% CI) | Relative effect (95% CI) | No of Participants (studies) | Quality of the evidence (GRADE) | Comments | |
| Assumed risk | Corresponding risk | |||||
| Placebo | Sulfasalazine | |||||
| Back pain (pooled data) 100 mm visual analogue scale, 0 = no pain, 100 = severe Follow‐up: median 26 weeks | The mean back pain (pooled data) in the control groups was 49.5 mm1 | The mean back pain (pooled data) in the intervention groups was 2.96 lower (6.33 lower to 0.41 higher) | 454 (6 studies) | ⊕⊕⊕⊝ Moderate2 | Absolute risk difference 3% lower (95% CI 1% to 6%); Relative percent change = 6% (95% CI 2% to 12%); NNT4 = n/a5 | |
| Mean improvement in Bath ankylosing spondylitis disease activity index (BASDAI) ‐ not reported | See comment | See comment | Not estimable | No data | See comment | Not measured |
| Mean improvement in Bath ankylosing spondylitis function index (BASFI) ‐ not reported | See comment | See comment | Not estimable | No data | See comment | Not measured |
| Mean improvement in Bath ankylosing spondylitis metrology index (BASMI) ‐ not reported | See comment | See comment | Not estimable | No data | See comment | Not measured |
| Radiographic progress ‐ not reported | See comment | See comment | Not estimable | No data | See comment | Not measured |
| Total number of withdrawals due to adverse events Follow‐up: median 26 weeks | 94 per 1000 | 134 per 1000 (98 to 182) | RR 1.43 (1.04 to 1.94) | 895 (11 studies) | ⊕⊕⊕⊝ Moderate2 | Absolute risk difference 4% (95% CI 0.4% to 8.8%); NNTH6 = 25 (95% CI 266 to 12) |
| Serious adverse events Follow‐up: mean 36 weeks | 0 per 1000 | 1 per 1000 (0 to 0) | OR 7.5 (0.15 to 378.16) | 264 (1 study) | ⊕⊕⊕⊝ Moderate3 | Absolute risk difference 750% (95% CI 15% to 37816%) (W); Relative percent change = 205% (95% CI ‐87% to 7309%); NNTH = n/a |
| *The basis for the assumed risk (e.g. the median control group risk across studies) is provided in footnotes. The corresponding risk (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI). CI: Confidence interval; RR: Risk ratio; OR: Odds ratio; | ||||||
| GRADE Working Group grades of evidence High quality: Further research is very unlikely to change our confidence in the estimate of effect. Moderate quality: Further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate. Low quality: Further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate. Very low quality: We are very uncertain about the estimate. | ||||||
1 From Clegg 1996, mean back pain at baseline in placebo = 48.9 (95% CI 3.0 to 94.8). 2 Different baseline value (3 as endpoint value and 3 as change from baseline value). 3 Wide confidence interval.
4 NNT (Number needed to treat). NNT for dichotomous outcomes calculated using Cates NNT calculator (http://www.nntonline.net/visualrx/).
5 n/a means result is not statistically significant.
6NNTH (Number needed to treat to harm).