bb‐Mrozek‐Budzyn 2010.

Study characteristics
Methods	Case‐control study, Poland
Participants	Participants were identified using general practitioner records in the Lesser Poland (Małopolska) Voivodeship in Poland. The sample population of this study included children aged 2 to 15 years diagnosed with childhood or atypical autism, classified according to ICD 10‐criteria as F84.0 or F84.1, respectively. Every diagnosis of autism was made by child psychiatrist. Dates of these diagnoses were recorded in general practitioner files. Cases with uncertain diagnosis of autism, secondary to disease state or trauma, were excluded. 2 controls were selected for each affected child, individually matched by year of birth, gender, and physician’s practice. The first 2 children who visited the physician after the time of the autistic child visit who met entry criteria served as controls. Cases: 96 children with childhood or atypical autism diagnosis aged between 2 and 15 years from Małopolska Province (southern Poland) Controls: 192 children matched for birth year, gender, and practice to the cases
Interventions	The Polish mandatory vaccinations schedule did not include MMR for all children until 2004. MMR vaccine and monovalent measles
Outcomes	Parents were interviewed by trained nurses using a standardised questionnaire. Questions for all children included information about prenatal and postnatal development, mental and physical development, chronic diseases, malformations and injuries, history of bowel disturbances, birth order, family size, and parents’ socioeconomic status. Parents of children with autism were additionally asked about the date of onset of symptom, the period when parents first suspected their child’s symptoms might be related to autism, and their knowledge and beliefs regarding the cause of autism. This questionnaire did not contain any questions concerning the child’s vaccination history so as to not bias the parent’s answers (i.e. insinuate a relationship with autism).
Funding Source	Government
Notes	Conclusion: the study provides evidence against the association of autism with either MMR or a single measles vaccine.
Risk of bias
Bias	Authors' judgement	Support for judgement
CCS ‐ case selection	Low risk	Adequate ‐ secure record ‐ general practitioner records
CCS ‐ control selection	Low risk	Adequate ‐ community control
CCS ‐ comparability	Unclear risk	Probable residual confounding ‐ matched for age, sex, and general practitioner
CCS ‐ exposures	Low risk	Adequate ‐ secure record
Summary Risk of Bias assessment	Unclear risk	We had concerns regarding at least 1 domain such that some doubt is raised about the results.