Table 4.

Performance of serum urate as a surrogate for gout flares according to the Bucher criteria [15]

Criteria	Answer	Evidence
Is there a strong independent, consistent association between the surrogate endpoint and the clinical endpoint?	Yes	Recent IPD analysis from two allopurinol RCTs shows clear relationship between achieving urate <0.36mmol/l and reduction in flares [24] Trials of febuxostat and allopurinol and pegloticase consistently show reduction in flares [1, 25]
Is there evidence from randomized trials in the same drug class that improvement in the surrogate end point has consistently led to improvement in the target outcome?	Yes	Trials of febuxostat and allopurinol consistently show reduction in flares [1, 25] Recent IPD analysis from two allopurinol RCTs shows clear relationship between achieving urate <0.36mmol/l and reduction in flares [24]
Is there evidence from randomized trials in other drug classes that improvement in the surrogate end point has consistently led to improvement in the target outcome?	(Yes)	Trials of febuxostat and allopurinol and pegloticase consistently show reduction in flares [1, 25]