| Study characteristics |
| Methods |
A nationwide case‐control study was conducted in New Zealand to test hypotheses about the role of infections in the aetiology of childhood leukaemia. |
| Participants |
The 131 eligible cases were newly diagnosed with childhood leukaemia (ages 0 to 14 years) 1990 to 1993, and born and resident in New Zealand. Controls (matched 1:1 to cases on age and sex) were selected randomly from the New Zealand‐born and resident childhood population, using national birth records. Each control’s birth was registered in the same quarter of the same year as the matched case. Adopted children were not eligible. |
| Interventions |
MMR vaccine not described. Vaccination histories were supplemented with information from parent‐held "Health and Development" records. |
| Outcomes |
Acute lymphoblastic leukaemia |
| Funding Source |
Government |
| Notes |
For MMR, no association was found with leukaemia. |
| Risk of bias |
| Bias |
Authors' judgement |
Support for judgement |
| CCS ‐ case selection |
Low risk |
Adequate ‐ based on population |
| CCS ‐ control selection |
Low risk |
Adequate ‐ community |
| CCS ‐ comparability |
Unclear risk |
Probable residual confounding ‐ matching for age and sex |
| CCS ‐ exposures |
Unclear risk |
Probable information bias ‐ vaccine not described ‐ standardised interview |
| Summary Risk of Bias assessment |
Unclear risk |
We had concerns regarding at least 1 domain such that some doubt is raised about the results. |
