Table II.

Evaluation of the methodological quality of the 11 studies included in the meta-analysis using an adapted version of the Newcastle-Ottawa Quality Assessment Scale (NOS).

Study	PCOS case definition adequate	Representativeness of PCOS cases	Selection of non- PCOS controls	Definition of non- PCOS controls	Comparability of both groups	Ascertainment of diagnosis	Same ascertainment method for both groups	Non-response rate	NOS score
Escobedo et al. (1991)	X	X	X	X	X	*	X	*	2
Schildkraut et al. (1996)	X	*	*	*	X	*	*	*	6
Anderson et al. (1997)	X	X	*	*	X	*	*	*	5
Talamini et al. (1997)	X	X	*	*	X	*	*	*	5
Niwa et al. (2000)	X	X	*	*	X	*	*	X	4
Iatrakis et al. (2006)	X	X	X	*	X	*	*	X	3
Olsen et al. (2008)	X	*	*	*	X	*	*	X	5
Zucchetto et al. (2009)	X	X	*	*	*	*	*	*	6
Fearnley et al. (2010)	X	*	*	*	X	*	*	X	5
Ghasemi et al. (2012)	*	X	X	*	X	*	*	X	4
Bodmer et al. (2011)	X	*	*	*	X	X	*	*	5

Note that the evaluation is in regards to being a sound study of PCOS rather than a sound study of cancer.

Note: ‘*’ indicates NOS quality assessment star awarded; ‘X’ indicates that no star was awarded.