Table 2 Newcastle-Ottawa Scale (NOS) risk of bias assessment for included studies
NOS (Newcastle-Ottawa Scale) risk of bias assessment for included studies | |||
|---|---|---|---|
Study ID | Von Rechlin et al. 1988 [22] | Tandberg et al. 1999 [23] | Katsulov 1983 [21] |
Representativeness of exposed cohort - Truly representative of the average woman (*) - Somewhat representative of the average woman (*) - Selected group of users -No description of the derivation of the cohort | |||
Selection of non-exposed cohort - Drawn from the same community as the exposed cohort (*) - Drawn from a different source - No description of the derivation of the non-exposed cohort | |||
Ascertainment of exposure - Secure records (e.g., surgical records) (*) - Structured interview (*) - Written self-report - No description | |||
Demonstration that outcome of interest was not present at the start of the study - Yes (*) - No | * | ||
Comparability of cohorts on the basis of the design or analysis - Study controls for gestational age and/or birth weight (*) - Study controls for any additional factor (*) | * | ||
Assessment of outcome -Independent blind assessment (*) - Record linkage (*) -Self-report -No description | * | * | |
Follow-up long enough for outcomes to occur - Yes (*) - No | * | * | * |
Adequacy of follow-up of cohorts - Complete follow-up – all subjects accounted for (*) - Subjects lost to follow-up unlikely to introduce bias, or description provided of those lost (*) - No statement | * | * | * |
Total number of stars | 2 | 5 | 3 |