Study	Selection				Comparability	Exposure			Score
	Is the case definition adequate?	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	☆
	a) Yes, with independent validation ☆	a) Consecutive or obviously representative series of cases ☆	a) Community controls ☆	a) No history of disease (endpoint) ☆	a) Study controls for_______ (Select the most important factor) ☆	a) Secure record (e.g. surgical records) ☆	a) Yes ☆	a) Same rate for both groups ☆
	b) Yes, e.g. record linkage or based on self reports	b) Potential for selection biases or not stated	b) Hospital controls	b) No description of source	b) Study controls for any additional factor (This criteria could be modified to indicate specific control for a second important factor) ☆	b) Structured interview where blind to case/control status ☆	b) No	b) Non respondents described
	c) No description		c) No description			c) Interview not blinded to case/control status		c) Rate different and no designation
						d) Written self report or medical record only
						e) No description
Da CL	☆	☆	☆	☆	☆	☆	☆		7
Song M	☆	☆		☆	☆	☆	☆		6
Zhang J	☆	☆		☆	☆	☆	☆		6
Luo H	☆	☆	☆	☆	☆	☆	☆		7
Hu X	☆	☆	☆	☆	☆	☆	☆		7
Suh JH	☆	☆	☆	☆	☆	☆	☆		7
Huang S	☆	☆	☆	☆	☆	☆	☆		7
Sun D	☆	☆	☆	☆	☆	☆	☆		7
Nambara S	☆	☆		☆	☆	☆	☆		6
Hong SA	☆	☆	☆		☆	☆	☆		6
Yu B	☆	☆	☆	☆	☆	☆	☆		7
Fan JH	☆	☆	☆	☆	☆	☆	☆		7
Fu Y	☆	☆	☆		☆	☆	☆		6
Bao SS	☆	☆	☆	☆	☆	☆	☆		7
Han XY	☆	☆		☆	☆	☆	☆		6
Xiao L	☆	☆	☆	☆	☆	☆	☆		7