bb Grimaldi‐Bensouda 2012.

Methods	Case‐control study
Participants	Cases (n = 198) were people with a diagnosis of immune thrombocytopenia (American Society of Hematology diagnostic criteria) identified with the collaboration of 22 university and major regional hospitals in France participating in the Pharmacoepidemiological General Research on ITP (PGRx‐ITP) registry project. Controls (n = 878) matched on age (2 years), sex, region of residence (northern or southern France), index date (date of first symptoms for the cases and date of consultation for the referents 2 months) from a random sample.
Interventions	Exposure to influenza vaccine. Assessed by structured interview and confirmed by vaccination records.
Outcomes	Immune thrombocytopenia
Notes	Government funded
Risk of bias
Bias	Authors' judgement	Support for judgement
CC ‐ case selection All outcomes	Low risk	Multicentre registry consecutive series of cases
CC ‐ control selection All outcomes	Unclear risk	Same population using registry from a sample of GPs
CC ‐ comparability All outcomes	Unclear risk	Matching 1:5
CC ‐ exposure All outcomes	Unclear risk	Structured interview ‐ confirmation by GPs
Summary assessment	Unclear risk	Unclear