Summary of findings 12. Safety: idiopathic thrombocytopenic purpura.
| Safety: idiopathic thrombocytopenic purpura | |||||
| Patient or population: children 9 months to 15 years old Setting: general population Intervention: MMR vaccine Comparison: unvaccinated | |||||
| Outcomes | Anticipated absolute effects* (95% CI) | Relative effect (95% CI) | № of participants (studies) | Certainty of the evidence (GRADE) | |
| Risk of ITP amongst unvaccinated | Risk of ITP amongst vaccinated | ||||
| Case‐control ‐ case cross‐over ‐ case controls MMR | Study population | OR 2.80 (1.50 to 5.23) | 410 cases, 2040 controls (2 observational studies) | ⊕⊕⊝⊝ LOW | |
| 0 per 1000 | 0 per 1000 (0 to 0) | ||||
| Self‐controlled case series ‐ MMR vaccine ‐ age from 9 to 23 months | Study population | Rate ratio 4.21 (2.28 to 7.78) | 3,723,677 (5 observational studies) | ⊕⊕⊕⊝ MODERATE1 | |
| 17 per 100,000 | 72 per 100,000 (39 to 132) | ||||
| *The risk in the intervention group (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI). CI: confidence interval; ITP: idiopathic thrombocytopenic purpura; MMR: measles, mumps, rubella vaccine; OR: odds ratio | |||||
| GRADE Working Group grades of evidence High certainty: We are very confident that the true effect lies close to that of the estimate of the effect. Moderate certainty: We are moderately confident in the effect estimate: the true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different. Low certainty: Our confidence in the effect estimate is limited: the true effect may be substantially different from the estimate of the effect. Very low certainty: We have very little confidence in the effect estimate: the true effect is likely to be substantially different from the estimate of effect. | |||||
1Upgraded one level due to large effect size