Clegg 1996.

Methods	Multicenter Randomized allocation Double‐blind allocation and assessment Parallel design Duration: 36 weeks Sample size at entry: 264 SSZ: 131 Placebo: 133 Clear description of withdrawal and drop‐outs Primary outcomes were analyzed according to intention‐to‐treat, secondary outcomes included only those who completed the trial
Participants	Participants fulfilling the modified New York criteria for definite AS Other inclusion criteria: 1. active spondylitis, defined as morning stiffness at least 45 min, inflammatory pain, patient and physician global assessment of disease activity of "moderate" or higher, failure to respond to a trial of aspirin or another NSAID 2. maintained on a stable dose of aspirin or another NSAID for at least 4 weeks Exclusion criteria: 1. evidence of complete ankylosis of the entire spine 2. other known causes of sacroiliitis 3. positive rheumatoid factor or anti‐nuclear antibody (> 1:80) 4. history of inflammatory bowel diseases or other rheumatic diseases 5. previously treated with SSZ 6. history of sensitivity to salicylates, sulfa‐containing drugs or tartrazine 7. with chronic diseases (according to the investigator) Age: 44.6 +/‐ 12.6 Male: 95% Duration of disease: 18.5 +/‐ 11.6 HLA B27: 81% With peripheral arthritis: 29%
Interventions	SSZ 1.0 g orally, twice a day Placebo 1.0 g orally, twice a day
Outcomes	Primary: 1. Response to treatment (event) 2. Improvement in physician global assessment (event) 3. Improvement in patient global assessment (event) 4. Improvement in morning stiffness (event) 5. Improvement in back pain (event) Secondary: 1. Night pain (no bother, event) 2. Duration of morning stiffness (hr) 3. Back pain (100 mm visual analogue scale) 4. Spondylitis function index (score 0 to 40) 5. Joint pain/tenderness score (0 to 198) 6. Joint swelling score (0 to 198) 7. Dactylitis score (0 to 3) 8. Enthesopathy index (0 to 90) 9. Spondylitis articular index (0 to 30) 10. Chest expansion (cm) 11. Modified Schober's test (cm) 12. Occiput‐to‐ wall test (cm) 13. Fingers‐to‐ floor test (cm) 14. ESR (mm/hr) 15. CRP (ug/mL) 16. Withdrawal due to side effect 17. Withdrawal due to ineffectiveness 17. Drop out for any reason
Notes	This trial was funded by Department of Veterans Affairs and Medical Research Service All continuous outcomes were presented as both end point and change from baseline Subgroup analysis: In participants without peripheral disease (N = 187), 40.2% of SSZ group and 43.3% of placebo group showed axial response In participants with peripheral diseases (N = 77), 32.4% of SSZ group and 20.9% of placebo group showed axial response, while 55.9% of SSZ group and 30.2% of placebo group showed peripheral response No description about the number under each intervention
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Insufficient information about the sequence generation process to permit judgment of Yes or No
Allocation concealment (selection bias)	Unclear risk	Insufficient information to permit judgment of Yes or No
Blinding (performance bias and detection bias) All outcomes	Low risk	"Patients received either 500 mg of enteric‐coated SSZ tablets or an identical placebo". "The following physical assessment was made by a clinician"
Incomplete outcome data (attrition bias) All outcomes	Low risk	"Withdrawals from the study were fewer than was anticipated by the Planning Committee". 36 patients from the SSZ group and 25 patients from the placebo group, the reasons for withdrawal were similar in both groups. The main study analysis based on intention‐to‐treat principles
Selective reporting (reporting bias)	Low risk	They reported the expected outcomes
Other bias	Low risk	The study appears to be free of other sources of bias