Table 3.

Methodological Quality of the Four Observational Cohort Studies

Study quality criteria	Monreal 199158	Rostoker 199559	Wawrzynska 2001&200360 , 61 *	Grzegorzewska 200857
Selection
Representativeness of the exposed cohort	-	-	-	-
Selection of the non-exposed cohort	-	-	-	-
Ascertainment of exposure	*	*	*	*
Demonstration that outcome of interest (i.e., bone outcome) was not present at start of study	*	-	*	-
Comparability
Comparability of cohorts on the basis of the design or analysis	-	-	-	**
Outcome (i.e., bone outcome)
Ascertainment of outcome	*	*	*	*
Follow-up long enough for outcomes to occur	*	*	*	*
Adequacy of follow-up of cohorts	*	-	-	*
NOS score	5/9	3/9	4/9	6/9
Additional criterion 1: large sample that provides sufficient statistical power to detect differences between the groups regarding fracture outcome	No	No	No	No
Additional criterion 2: bone outcome assessed as secondary	No	Yes	No	No

^*Two published articles^{60 , 61} done by the same authors were evaluated together; dash (−) denotes blank cell and no star; NOS = Newcastle Ottawa Scale