Palferman 1991.

Methods	Design: RCT Number of centres: 2 Treatment duration: 3 months Flare design: No Wash‐out period: Yes (with Paracetamol as escape) Time point of assessments: BL, 1, 2, 3 months
Participants	Inclusion criteria: 1. Over sixteen years of age; 2. Satisfied the Rome criteria for AS Exclusion criteria: 1. Pregnant; 2. Receiving concomitant treatment with hydantoins or sulphonamides; 3. Receiving prednisolone in excess of 7.5 mg daily; 4. History of indomethacin intolerance; 5. Renal or hepatic impairment. Classification: Rome criteria Nabumetone (2000 mg): Number of participants: 23 Number of completers: 14 Age (mean): 40 Male (%): 87 Symptom duration: NA Disease duration (mean): 13.7 years HLA‐B27 positive (%): NA Indomethacin (150 mg): Number of participants: 19 Number of completers: 10 Age (mean): 40 Male (%): 58 Symptom duration: NA Disease duration (mean): 14.64 years HLA‐B27 positive (%): NA
Interventions	Nabumetone (2000 mg) vs Indomethacin (150 mg) Co‐medication: Not reported
Outcomes	Extracted outcomes: Withdrawals due to adverse events Chest expansion Tragus‐to‐wall distance Schober's test Number of any adverse events
Notes	Funding source: Not reported
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	"…they were randomised to one of the two groups..." No information was provided on sequence generation.
Allocation concealment (selection bias)	Unclear risk	No information was provided on allocation concealment.
Blinding of participants and personnel (performance bias) All outcomes	High risk	"…to one of the two groups and treatment started with either indomethacin 50 mg tds or nabumetone 1 g bd." No actions were undertaken to blind participants from their allocated treatment.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	No information provided on blinding of outcome assessors.
Incomplete outcome data (attrition bias) All outcomes	High risk	"If a patient withdrew from the study prior to month three, the data from the last assessment was used." "Eighteen patients withdrew early, that is, before the three month assessment…" Although actions were undertaken to impute for missing data, the level of missing data was considerable in both groups.
Selective reporting (reporting bias)	High risk	Spinal pain (on a 0 to 3 graded scale) was measured but not reported in the results.
Other bias	High risk	There was some BL imbalance that was not adjusted for in the analyses.