Meta-analysis of the association between chronic periodontitis and chronic kidney disease

Table 4 Newcastle–Ottawa Scale scores of the cohort study literature

Ref.	Study population selection				Comparability between groups	Outcome measurement			Total points
	Representativeness of the exposed group	Selection of non-exposed groups	Identification of exposure factors	No outcome indicators were available before the study began	Comparability of the resulting cohort based on design and analysis	Methods of evaluating outcome events	Whether the follow-up time was sufficient	Integrity of follow-up
Sharma et al[15]	1	1	1	1	1	1	1	1	8
Grubbs et al[16]	0	1	1	1	1	1	1	1	7
Grubbs et al[17]	1	1	1	1	1	1	1	1	8
Chen et al[18]	1	1	1	1	1	1	1	1	8
Li et al[19]	1	1	1	1	1	1	1	1	8