Table 3 Newcastle-Ottawa quality assessment scale for before-after observational studies.

Representativeness of the exposed cohort

Selection of the non-exposed cohort

Ascertainment of exposure

Outcome of interest not present at the start of study

Cohorts comparable on the basis of design or analysis

Assessment of outcome

Adequacy of duration of follow-up

Adequacy of completeness of follow-up

Rao et al., 1997 [17]

*

*

*

*

Price et al., 1999 [18]

*

*

*

*

*

*

Leong et al., 2000 [19]

*

*

*

*

*

Krinsley et al., 2003 [20]

*

*

*

*

*

*

Graat et al., 2007 [21]

*

*

*

*

*

Hendrikse et al., 2007 [22]

*

*

*

*

*

*