Table 3.

The Newcastle-Ottawa Scale (NOS) for assessing the quality of all cohort studies involved in this meta-analysis

First author	Published year	Representative of the exposed cohort	Selection of the non-exposed cohort	Ascertainment of exposed	Demonstration that outcome of interest was no present at start of study	Control for important cohort	Additional factors	Assessment of outcome	Follow up	Adequacy of follow up	Score
Kaplan	1987	1	1	0	1	1	1	1	1	1	8
Seki	2001	1	1	0	1	1	1	1	1	1	8
Goto	2003	1	1	0	1	1	1	1	1	0	7
Lan	2007	1	1	0	1	1	1	1	1	0	7
Gangwisch	2008	1	1	0	1	1	1	1	1	0	7
Stone	2009	1	1	0	1	1	1	1	1	1	8
Suzuki	2009	1	1	0	1	1	1	1	1	1	8
Kronholm	2011	1	1	0	1	1	0	1	1	0	6
Werle	2011	1	1	0	1	0	1	1	1	0	6
Kripke	2011	1	1	1	1	1	0	1	1	1	8
Castro-Costa	2011	1	1	0	1	1	1	1	1	0	7
Qiu	2011	1	1	0	1	1	1	1	1	1	8
Cohen-Mansfield	2012	1	1	0	1	1	1	1	1	1	8
Jung	2013	1	1	0	1	1	1	1	1	1	8
Kim	2013	1	1	0	1	1	1	1	1	0	7
Yeo	2013	1	1	0	1	1	1	1	1	0	7
Kakizaki	2013	1	1	0	1	1	1	1	1	1	8
Chen	2013	1	1	0	1	1	1	1	1	1	8
Lee	2014	1	1	0	1	1	1	1	1	0	7
Zuurbier	2015	1	1	1	1	1	1	1	1	1	9
Hall	2015	1	1	0	1	1	1	1	1	0	7
Smagula	2016	1	1	1	1	1	1	1	1	1	9
Akersted	2017	1	1	0	1	1	1	1	1	0	7
Beydoun	2017	1	1	0	1	1	1	1	1	0	7
Brostrom	2018	1	1	0	1	1	0	1	1	1	7
Cheng	2018	1	1	0	1	1	1	1	1	0	7
Morgan	2019	1	1	0	1	1	1	1	1	1	8
Akersted	2019	1	1	0	1	1	1	1	1	0	7