Table 2

Risk of bias assessment of CS

  1. Are study groups clearly defined?

  2. Is there any selection bias?

  3. Is the exposure clearly defined?

  4. Is the outcome clearly defined?

  5. Is the outcome assessment blinded?

  6. Is the follow-up accurate?

  7. Is there an acceptable loss-to-follow-up?

  8. Are confounders described and/or eliminated?