Table 2.

Newcastle–Ottawa quality-assessment scale scores

	Reference	Score
1	Park-Wyllie et al 200627	8 out of 8
2	Mohr et al 200824	8 out of 8
3	Mohr et al 200523	8 out of 8
4	Graumlich et al 200517	7 out of 8
5	Etminanet et al	7 out of 8
6	Schelleman et al 201028	8 out of 8
7	Parekh et al 201426	8 out of 8
8	Aspinall et al 200913	8 out of 8
9	Chou et al 201314	8 out of 8
10	LaPlante et al 200820	7 out of 8
11	Lodise et al 200721	7 out of 8
12	Onyenwenyi et al 200725	8 out of 8
13	Haerian et al 200718	7 out of 8

Notes: 1–5, case–control studies; 6–12, cohort studies.