Timing of surgical operation for patients with intra-abdominal infection: A systematic review and meta-analysis

Table 2 Results of quality assessment using the Newcastle-Ottawa Scale for case-control studies

Ref.	Selection				Comparability	Exposure			Quality score
	Adequate definition of cases	Representativeness of the cases	Selection of controls	Definition of controls	Comparability of cases and controls on the basis of the design or analysis	Ascertainment of exposure	Same method of ascertainment for cases and controls	Non-Response rate
Elramah et al[24]	1	1	-	1	1	1	1	1	7
Giraudo et al[23]	1	1	-	1	1	1	1	1	7
Lee et al[25]	1	1	-	1	1	1	1	1	7
Maroju et al[28]	1	1	-	1	1	1	1	1	7
Kim et al[29]	1	1	-	1	1	1	1	1	7
Saar et al[30]	1	1	-	-	2	1	1	1	7
Rause et al[22]	1	1	-	-	1	1	1	1	6
Azuhata et al[26]	1	1	-	1	2	1	1	1	8
Wen and Tang[27]	1	1	-	1	2	1	1	1	8

¹Indicates that the inclusion study met the relevant criteria and represents a score of 1.

²Indicates that the inclusion study met the relevant criteria and represents a score of 2.