ba Eisenberg 2008b.

Methods	See Eisenberg 2008a
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	Same population
CC‐Comparability	Low risk	Adjustment by confounders
CC‐Exposure	Low risk	Secure record
Summary assessments	Low risk	Plausible bias unlikely to seriously alter the results