Bias in selection of participants into the study 2.1. Was selection of participants into the (or into the analysis) based on variables measured after the start of the exposure? If N or PN to 2.1 go to 2.4 Y / PY / PN / N / NI [Description] 2.2. If Y/PY to 2.1: Were the post-exposure variables that influenced selection associated with exposure? Y / PY / PN / N / NI [Description] 2.3. If Y/PY to 2.2: Were the post-exposure variables that influenced eligibility selection influenced by the outcome or a cause of the outcome? NA / Y / PY / PN / N / NI [Description] 2.4 Do start of follow-up and start of exposure coincide for most participants? NA / Y / PY / PN / N / NI [Description] 2.5 If Y/PY to 2.2 and 2.3, or N/PN to 2.4: Were adjustment techniques used that are likely to correct for the presence of selection biases? NA / Y / PY / PN / N / NI [Description] Risk of bias judgement Low / Moderate / Serious / Critical / NI [Support for judgement] Optional: What is the predicted direction of bias due to selection of participants into the study? Favors experimental / Favors comparator / Towards null /Away from null / Unpredictable [Rationale] Bias in classification of exposures 3.1 Is exposure status well defined? Y / PY / PN / N / NI [Description] 3.2 Did entry into the study begin with start of the exposure? Y / PY / PN / N / NI [Description] 3.3 Was information used to define exposure status recorded prior to outcome assessment? Y / PY / PN / N / NI [Description] 3.4 classification of exposure status have been affected by knowledge of the outcome or risk of the outcome? Y / PY / PN / N / NI [Description] 3.5 Were exposure assessment methods robust (including methods used to data)? Y / PY / PN / N / NI [Description] Risk of bias judgement Low / Moderate / Serious / Critical / NI [Support for judgement]
Optional: What is the predicted direction of bias due to measurement of outcomes or exposures? Favors experimental / Favors comparator / Towards null /Away from null / Unpredictable [Rationale] Bias due to departures from intended exposures 4.1. Is there concern that changes in exposure status occurred among participants? If your aim for this is to assess the effect of initiating and adhering to an exposure (as in a per-protocol analysis), answer questions 4.2 and 4.3, otherwise continue to 4.4 if Y or PY to 4.1. Y / PY / PN / N / NI [Description] 4.2. Did many participants switch to other exposures? Y / PY / PN / N / NI [Description] 4.3. Were the critical co-exposures balanced across exposure groups? Y / PY / PN / N / NI [Description] 4.4. If NY/PN PY to 4.1, or Y/PY to 4.2, or 4.3: Were adjustment techniques used that are likely to correct for these issues? NA / Y / PY / PN / N / NI [Description] Risk of bias judgement Low / Moderate / Serious / Critical / NI [Support for judgement] Optional: What is the predicted direction of bias due to departures from the intended exposures? Favors experimental / Favors comparator / Towards null /Away from null / Unpredictable [Rationale] Bias due to missing data 5.1 Were there missing outcome data? Y / PY / PN / N / NI [Description] 5.2 Were participants excluded due to missing data on exposure status? Y / PY / PN / N / NI [Description] 5.3 Were participants excluded due to missing data on other variables needed for the analysis? Y / PY / PN / N / NI [Description] 5.4 If Y/PY to 5.1, 5.2 or 5.3: Are the proportion of participants and reasons for missing data similar across exposures? NA / Y / PY / PN / N / NI [Description] 5.5 If Y/PY to 5.1, 5.2 or 5.3: Were appropriate statistical methods used to account for missing data? NA / Y / PY / PN / N / NI [Description]