Table 2 NOS scale for observational studies

Cohort studies

Baseline

Selection

Comparability

Outcome

Quality Score

Study Title

First Author

Year

Study Design (Prospective or retrospective)

mean follow up

Sample (n) (comp/control)

Age at baseline mean (Year) (comp/control)

Representativeness of the exposed cohort

Selection of the non-exposed cohort

Ascertainment of exposure

Demonstration that outcome of interest was not present at start of study

Comparability of cohorts on the basis of the design or analysis

Assessment of outcome

Was follow-up long enough for outcomes to occur

Adequacy of follow up of cohorts