1. Effect modifiers for meta‐regression of change in post‐operative serum creatinine.

Study ID	Cardiac surgery	NSAIDs > 24 hours	Age exclusion
Eljezi 2017	Yes	Yes	> 75 years
Fayaz 2004	Yes	No	None reported
Hynninen 2000	Yes	No	> 75 years
Immer 2003	Yes	Yes, 3 days	> 70 years
Kostamovaara 1996	No, hip or knee replacement	No	None reported
Kulik 2004	Yes	Yes, 5 days	None reported
Laisalmi 2001a	No, breast surgery	No	None reported
Perttunen 1992	No, thoracoscopy	Yes, 2 days	> 75 years
Perttunen 1999	No, thoracoscopy	Yes, 2 days	> 75 years
Power 1992	No, oesophagogastrectomy	Yes, 2 days	None reported
Puolakka 2009	No, laparoscopic hysterectomy	No	None reported
Rafiq 2014	Yes	Yes, 4 days	None reported
Rapanos 1999	Yes	No	None reported
Turner 1994	No, cholecystectomy	Yes, 3 days	None reported
Varrassi 1994	No, cholecystectomy	No	> 65 years

NSAIDs ‐ nonsteroidal anti‐inflammatory drugs