| Methods |
Multicentre, case‐control study |
| Participants |
Cases (n = 104): Guillain‐Barré syndrome cases (Brighton Collaboration definition, levels 1 to 3).
Controls (n = 1198): each case was matched to up to 25 controls on age (plus or minus 1 year), sex, index date, and country. Matched controls recruited in the Netherlands, Sweden, the UK, France, and Denmark. |
| Interventions |
Exposure to monovalent pandemic H1N1 2009 to 2010 influenza vaccine during the 6 months preceding the index date. Vaccination data were obtained from vaccine registries (Denmark and France), from general practitioner records (UK and Netherlands), and from structured interviews (Sweden). |
| Outcomes |
Guillain‐Barré syndrome |
| Notes |
This study was funded by the European Centre for Disease Prevention and Control. |
| Risk of bias |
| Bias |
Authors' judgement |
Support for judgement |
| CC ‐ case selection
All outcomes |
Low risk |
Neurological clinic registry |
| CC ‐ control selection
All outcomes |
Unclear risk |
From the same population using only general practitioner registry |
| CC ‐ comparability
All outcomes |
Unclear risk |
Poor matching |
| CC ‐ exposure
All outcomes |
Unclear risk |
Interview and record linkage |
| Summary assessment |
Unclear risk |
Unclear |
