Table 2.

Assessment of study quality

First author [Ref.]	Selection				Comparability		Exposure			Score
	1	2	3	4	5a	5b	6	7	8
Charuhas [19]	yes	yes	no	no	yes	yes	yes	yes	no	6
Ilknur [17]	yes	yes	no	yes	yes	yes	yes	yes	no	7
Sirvinskas [14]	yes	yes	no	yes	yes	yes	yes	no	no	6
Haase [15]	yes	yes	no	no	yes	yes	yes	yes	no	6
Loef [20]	yes	yes	no	yes	yes	yes	yes	yes	no	7
Rodrigues [16]	yes	yes	no	yes	yes	yes	yes	yes	no	7
Suen [13]	yes	yes	no	no	yes	yes	yes	yes	no	6
Bove [18]	yes	yes	no	yes	yes	yes	yes	yes	no	7
Lin [21]	yes	yes	no	no	yes	yes	yes	yes	no	6
Han [22]	yes	yes	no	yes	no	yes	no	yes	no	5
Yang [23]	yes	yes	no	yes	no	yes	yes	yes	no	6
Englberger [24]	yes	yes	no	yes	yes	yes	yes	yes	no	7
Karkouti [25]	yes	yes	no	yes	yes	yes	yes	yes	no	7
Landoni [26]	yes	yes	no	yes	yes	yes	yes	yes	no	7

For case-control studies: 1 = cases were independently validated; 2 = cases are consecutive or representative of a population; 3 = community controls; 4 = controls had no history of renal insufficiency; 5a = study controlled for age and CPB time; 5b = study controlled for any additional factor(s); 6 = ascertainment of exposure by secure record or structured interview where the interviewer was blinded to case/control status; 7 = same method of ascertainment for cases and controls; 8 = same nonresponse rate for cases and controls.