. 2017 Jul 13;3(3):169–175. doi: 10.1016/j.cdtm.2017.06.001

Table 2.

Methodological quality of retrospective cohort studies.

Authors	Representativeness of the exposed cohort	Selection of the unexposed cohort	Ascertainment of exposure	Outcome of interest not present at start of study	Control for important factor or additional factor	Outcome assessment	Follow–up long enough for outcomes to occur	Adequacy of follow–up of cohorts	Total quality scores
Spillane et al¹⁹	+	+	+	+	++	+	−	+	8
Zanders et al²⁰	+	+	+	+	++	+	+	−	8
Cossor et al²¹	+	+	+	+	+	+	−	−	6
Fransgaard et al²²	+	+	+	+	+	+	+	+	8
Mc Menamin et al²³	+	+	+	+	++	+	+	−	8
Garrett et al²⁴	+	+	+	+	+	+	+	+	8
Lee et al²⁵	+	+	+	+	+	+	+	−	7
Paulus et al²⁶	+	+	+	+	++	+	+	−	8