| Study characteristics |
| Methods |
Case cross‐over, France. To compare the frequency of exposure to vaccines during a 6‐week interval immediately preceding the event (case period) to the frequency of exposure during prior 2 control time intervals (named control periods, 6 and 3 months before the case period, having the same duration as the case period) |
| Participants |
Population‐based study in France including all children newly diagnosed for primary ITP between July 2009 and June 2015 |
| Interventions |
MMR vaccines, combined vaccines containing diphtheria, tetanus, and poliomyelitis (DTP), as well as pneumococcal, meningococcal, and hepatitis B (HBV) vaccines |
| Outcomes |
Immune thrombocytopenia |
| Funding Source |
Not stated |
| Notes |
Conclusion: in this nationwide study, no significant risk was observed for vaccines against DTP, pneumococcus, meningococcus, and HBV. The increased risk of MMR‐induced ITP is shown in children (previously demonstrated as lower than after the natural infection with measles). Vaccine‐induced ITP remains an exceptional adverse drug reaction, including for MMR vaccines. |
| Risk of bias |
| Bias |
Authors' judgement |
Support for judgement |
| CCO ‐ case selection |
Unclear risk |
There was insufficient information. |
| CCO ‐ exposure |
Unclear risk |
There was insufficient information. |
| CCO ‐ risk and control periods |
Unclear risk |
There was insufficient information. |
| CCO ‐ comparability |
Unclear risk |
There was insufficient information. |
| Summary Risk of Bias assessment |
Unclear risk |
We had concerns regarding at least 1 domain such that some doubt is raised about the results. |
