ba Staat 2011b.

Methods	See Staat 2011a
Participants
Interventions
Outcomes
Funding Source
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
CC‐Case Selection	Low risk	Independent validation
CC‐Control Selection	Low risk	Drawn from the same population
CC‐Comparability	Unclear risk	Matched
CC‐Exposure	Low risk	Secure record and interview
Summary assessments	Unclear risk	Plausible bias that raises some doubt about the results