| Methods |
Case‐control surveillance study |
| Participants |
Cases (n = 169): patients 18 years of age or older with a diagnosis of certain or probable immune thrombocytopenia. Of the included 169 cases, 130 were outpatients and 39 were inpatients.
Controls (n = 770): 731 outpatients and 39 inpatients selected from the same hospitals as the cases. The index date for outpatient controls was defined as the date of hospitalisation or the date of initiation of the control disease episode if this preceded hospitalisation. The index date for inpatient controls was the date of the interview. |
| Interventions |
Exposure to influenza vaccination during the 28 days preceding the index date. Exposure to other vaccines and drugs was also considered. |
| Outcomes |
Immune thrombocytopenia |
| Notes |
Government funded |
| Risk of bias |
| Bias |
Authors' judgement |
Support for judgement |
| CC ‐ case selection
All outcomes |
Low risk |
Hospital population |
| CC ‐ control selection
All outcomes |
Low risk |
Hospital control |
| CC ‐ comparability
All outcomes |
Unclear risk |
No matching |
| CC ‐ exposure
All outcomes |
Unclear risk |
Unclear |
| Summary assessment |
Unclear risk |
Unclear |
