Table 2.

Newcastle Ottawa Scale for included studies

	SELECTION					EXPOSURE
	Is the case definition adequate?	Representativeness of the cases	Selection of controls	Definition of controls	COMPARABILITY	Ascertainment of exposure	Same method of ascertainement for cases and controls	Non response rate	Total score (max 9 stars)
Ascherio	1	1	1	1	2	0	1	0	7
Eftekarian	0	0	0	0	2	0	0	0	2
Hernan	1	1	1	1	2	0	1	1	8
Langer-Gould	1	1	1	0	2	0	1	1	7
Mikaeloff	1	1	1	1	2	0	1	0	7
Ramagoplan	1	0	1	1	2	0	1	0	6
Touze	1	1	1	1	2	1	1	0	8