Muller‐Fassbender 1985.

Methods	Design: Cross‐over study Number of centres: NA Treatment duration: each treatment period was 6 weeks Flare design: No Wash‐out period: No Time point of assessments: BL, 1, 2, 3, 4, 5, 6 weeks
Participants	Inclusion criteria: None reported. Exclusion criteria: 1. Severe damage to the liver parenchyma or decreased kidney functioning; 2. History of peptic ulcer; 3. Pregnancy. Classification: NA Ketoprofen (2 times 150 mg): Number of participants: 20 Number of completers: NA Ketoprofen (3 times 100 mg): Number of participants: 19 Number of completers: NA All participants: Age (mean): 42.7 Male (%): 95 Symptom duration: NA Disease duration: NA HLA‐B27 positive (%): NA
Interventions	Ketoprofen (2 times 150 mg) vs Ketoprofen (3 times 100 mg) Co‐medication: No other anti‐inflammatory drugs were allowed.
Outcomes	Extracted outcomes: None
Notes	The study was not included in the meta‐analysis, because no outcomes could be extracted. The outcomes pain on Likert scale, chest expansion and Schober's test were presented, but these data could not be used due to presentation in graphs from which the data could not be extracted. The authors state that they only used and reported the data from the first part of the cross‐over study, because they could not exclude a cross‐over effect in the second part of the cross‐over. Funding source: Not reported
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	No information is provided on sequence generation.
Allocation concealment (selection bias)	Unclear risk	No information provided on allocation concealment.
Blinding of participants and personnel (performance bias) All outcomes	Low risk	"Als behandlung A erhielten die Patienten morgens und abends je 1 kapsel mit 150mg Ketoprofen und mittags 1 Placebokapsel…" Patients were blinded from their allocated treatment and received a placebo capsule.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	"In a randomized, double‐blind cross‐over study…" No further information is provided on blinding of outcome assessors.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Outcome data from the first part of the cross‐over study was available from all participants.
Selective reporting (reporting bias)	Low risk	All outcomes stated in the methods are reported.
Other bias	Unclear risk	Unable to detect other causes of bias due to the way the data is presented.