Caldwell 1986.

Methods	Design: CCT Number of centres: NA ("multicenter") Treatment duration: 6 months Flare design: Yes Wash‐out period: Yes (until flare) Time point of assessments: BL, 2 weeks, 4 weeks and 2, 3, 4, 5, 6 months
Participants	Inclusion criteria: 1. Age 18 or over; 2. Diagnosis of AS for minimal 6 months; 3. At least 2 of the following: a) lumbar or dorsal lumbar junction pain and stiffness of over 3 months duration, b) major limitation of motion of lumbar spine in 3 directions (flexion‐extension, lateral bending and rotation), c) pain and stiffness in the thoracic region of over 3 months duration, d) nocturnal pain with morning stiffness or bilateral pain in buttocks, or both, or pain in either buttock; 4. Grade 2 or 3 bilateral sacroiliitis by the following X‐ray criteria: 0 = normal, 1 = suspicious, 2 = definitely abnormal, 3 = advanced abnormal; 5. HLA‐B27 positive; 6. ESR ≥ 18 mm/hr; 7. Rheumatoid factor titre ≤ 1/80; 8. Normal serum uric acid level (unless patient was receiving thiaxide diuretic therapy or had gouty arthritis); 9. Muscle spasm in the back and decreased range of motion of some part of the spine. Exclusion criteria: 1. Unable to walk 50 feet; 2. Receiving anticoagulant therapy; 3. Women of childbearing potential; 4. Patients with known allergies to aspirin or other NSAIDs, or both; 5. Coexisting gastrointestinal, inflammatory, malignant, or infectious diseases and renal or hepatic impairment. Classification: NA Oxaprozin (1200 mg): Number of participants: 55 Number of completers: 36 Indomethacin (50 to 150 mg): Number of participants: 42 Number of completers: 31 All participants: Age: 40 (range 19 to 70) Male (%): 84 Symptom duration: NA Disease duration: 11 (range 1 to 40) years HLA‐B27 positive (%): NA
Interventions	Oxaprozin (1200 mg) vs Indomethacin (50 to 150 mg) Co‐medication: Concomitant corticosteroid therapy (max 7.5 mg prednisone daily), pure analgesics having no anti‐inflammatory effect and medication for unrelated illnesses that had begun at least 3 months before study entry.
Outcomes	Extracted outcomes: 1. Pain on Likert scale (BL, 2 weeks, post‐treatment after 6 months) (scale 0 to 4, higher is worse) Oxaprozin 1200 mg: 2.02 (N = 47), 1.62 (N = 47), 1.19 (N = 21) (P = not significant) Indomethacin 25 to 50 mg: 2.19 (N = 32), 1.38 (N = 32), 0.94 (N = 17) (P < 0.05 at 2 weeks, P < 0.001 post‐treatment) 2. Withdrawals due to adverse events 3. Patient's global assessment of disease activity (BL, 2 weeks, post‐treatment after 6 months) (scale 1 to 5, higher is worse) Oxaprozin 1200 mg: 3.09 (N = 47), 2.70 (N = 47), 2.18 (N = 22) (P < 0.05 at 2 weeks) Indomethacin 25 to 50 mg: 3.31 (N = 32), 2.47 (N = 32), 2.35 (N = 17) (P < 0.001 at 2 weeks, P < 0.01 post‐treatment) 4. Duration of morning stiffness (BL, 2 weeks, post‐treatment after 6 months) (median, in minutes, higher is worse) Oxaprozin 1200 mg: 120.0 (N = 48), 90.0 (N = 48), 15.0 (N = 22) (P < 0.001 post‐treatment) Indomethacin 25 to 50 mg: 120.0 (N = 32), 60.0 (N = 32), 20.0 (N = 17) (P < 0.01 at 2 weeks) 5. Lateral spinal flexion (BL, 2 weeks, post‐treatment after 6 months) (in cm, left‐sided, higher is better) Oxaprozin 1200 mg: 4.9 (N = 43), 5.8 (N = 43), 5.9 (N = 20) (P = not significant) Indomethacin 25 to 50 mg: 8.0 (N = 31), 8.2 (N = 31), 5.3 (N = 17) (P = not significant) 6. Chest expansion (BL, 2 weeks, post‐treatment after 6 months) (in cm, higher is better) Oxaprozin 1200 mg: 2.8 (N = 47), 3.3 (N = 47), 4.0 (N = 21) (P < 0.05 at 2 weeks, P < 0.01 post‐treatment) Indomethacin 25 to 50 mg: 2.8 (N = 30), 3.2 (N = 30), 3.2 (N = 16) (P = not significant) 7. Occiput‐to‐wall distance (BL, 2 weeks, post‐treatment after 6 months) (in cm, higher is worse) Oxaprozin 1200 mg: 5.2 (N = 43), 5.2 (N = 43), 7.8 (N = 17) (P = not significant) Indomethacin 25 to 50 mg: 3.7 (N = 29), 3.2 (N = 29), 2.2 (N = 15) (P = not significant) 8. Intermalleolar distance (BL, 2 weeks, post‐treatment after 6 months) (in cm, higher is better) Oxaprozin 1200 mg: 103.5 (N = 46), 102.2 (N = 46), 107.1 (N = 21) (P = not significant) Indomethacin 25 to 50 mg: 102.1 (N = 30), 105.5 (N = 30), 109.1 (N = 17) (P = not significant) 9. Schober's test (BL, 2 weeks, post‐treatment after 6 months) (in cm, higher is better) Oxaprozin 1200 mg: 4.7 (N = 43), 5.7 (N = 43), 5.3 (N = 20) (P = not significant) Indomethacin 25 to 50 mg: 6.5 (N = 30), 7.6 (N = 30), 4.8 (N = 17) (P = not significant) 10. Number of any adverse events 11. Number of adverse events per organ system
Notes	Outcomes that were not included in the meta‐analysis, because no measure of variance (SD, SE or CI) was reported for these outcomes: pain on Likert scale, patient's global assessment of disease activity, duration of morning stiffness, lateral spinal flexion, chest expansion, occiput‐to‐wall distance, intermalleolar distance, Schober's test. Available results are described in this table. For the outcome number of adverse events per organ system only the most frequently occurring adverse events were reported per organ system, adverse events judged as not drug‐related were excluded. Funding source: Not reported
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	High risk	No comment is made by the authors anywhere that patients were randomised.
Allocation concealment (selection bias)	High risk	No comment is made by the authors anywhere that patients were randomised.
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	"double‐blind". Probably done, but no further information was provided on blinding of participants.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	"double‐blind". Probably done, but no further information was provided on blinding of outcome assessors.
Incomplete outcome data (attrition bias) All outcomes	High risk	"Nineteen patients (35%) in the oxaprozin group and 11 (26%) in the indomethacin group discontinued treatment for drug‐related reasons including unsatisfactory response and/or adverse effects". In table 3 with results every outcome has another number of participants without explanation why the other patients did not provide data, also many patient data are not available for outcomes post‐treatment (up to 83% loss‐to‐follow‐up).
Selective reporting (reporting bias)	Low risk	All pre‐specified outcomes according to the methods section, are reported in the results section.
Other bias	Low risk	No other bias was detected.