Criterion	Evidence	Decision
Risk of bias	Eight studies had high risk of bias overall or high risk of attrition bias	Not serious: the mean difference in SCr was higher in the six studies with low or unclear risk of bias (3.45, 0.12 to 6.78) than in all 15 studies (3.23, ‐0.80 to 7.26)
Imprecision	794 participants	Not serious
Inconsistency	Chi2 = 40.98, df = 14 (P = 0.0002); I2 = 66%	Serious: the inconsistency was not adequately explained by pre‐specified effect modifiers (Table 2)
Indirectness	All of the studies had multiple exclusion criteria, including age in 6 (Table 2)	Serious: the patients in these RCTs are likely to be different from those in routine care. The results of Kulik 2004 (decrease in SCr associated with naproxen for 5 days after cardiac surgery) are in stark contrast to the results of NAFARM 2011 (trial stopped because of excess risk of acute kidney injury associated a lower dose of naproxen for 5 days after cardiac surgery)
Publication bias	None of the studies were commercially sponsored	Not serious