Modified Newcastle-Ottawa Quality Assessment Scale for Cohort studies included in the Meta-analysis

*Selection:
(1) Representativeness of the exposed cohort: A, truly representative; B, somewhat representative; C, selected group; D, no description of the derivation of the cohort.
(2) Selection of the non-exposed cohort: A, drawn from the same community as the exposed cohort; B, drawn from a different source; C, no description of the derivation of the non-exposed cohort.
(3) Ascertainment of exposure: A, secure record; B, structured interview; C, written self-report; D, no description.
(4) For demonstration that the outcome of interest was not present at start of study: A, yes; B, no.
•Comparability: For comparability of cohorts on the basis of the design or analysis: A, study controls for co-morbidities; B, study controls for any additional factor (e.g., age and severity of illness); C, not done.
0Outcome:
(1) Assessment of outcome: A, independent blind assessment; B, record linkage; C, self-report; D, no description.
(2) Was follow-up long enough for outcomes to occur? A, yes, (i.e. in-hospital or up to 30 d); B, no.
(3) Adequacy of follow-up of cohorts: A, complete follow-up and all subjects accounted for; B, subjects lost to follow-up was unlikely to introduce bias, because a small number were lost or a description was provided of those lost; C, follow-up rate 90% or lower (select an adequate percentage) and no description of those lost; D, no statement.