Autism occurrence by MMR vaccine status among US children with older siblings with and without autism.

IMPORTANCE: Despite research showing no link between the measles-mumps-rubella (MMR) vaccine and autism spectrum disorders (ASD), beliefs that the vaccine causes autism persist, leading to lower vaccination levels. Parents who already have a child with ASD may be especially wary of vaccinations. OBJECTIVE: To report ASD occurrence by MMR vaccine status in a large sample of US children who have older siblings with and without ASD. DESIGN, SETTING, AND PARTICIPANTS: A retrospective cohort study using an administrative claims database associated with a large commercial health plan. Participants included children continuously enrolled in the health plan from birth to at least 5 years of age during 2001-2012 who also had an older sibling continuously enrolled for at least 6 months between 1997 and 2012. EXPOSURES: MMR vaccine receipt (0, 1, 2 doses) between birth and 5 years of age. MAIN OUTCOMES AND MEASURES: ASD status defined as 2 claims with a diagnosis code in any position for autistic disorder or other specified pervasive developmental disorder (PDD) including Asperger syndrome, or unspecified PDD (International Classification of Diseases, Ninth Revision, Clinical Modification 299.0x, 299.8x, 299.9x). RESULTS: Of 95,727 children with older siblings, 994 (1.04%) were diagnosed with ASD and 1929 (2.01%) had an older sibling with ASD. Of those with older siblings with ASD, 134 (6.9%) had ASD, vs 860 (0.9%) children with unaffected siblings (P < .001). MMR vaccination rates (≥1 dose) were 84% (n = 78,564) at age 2 years and 92% (n = 86,063) at age 5 years for children with unaffected older siblings, vs 73% (n = 1409) at age 2 years and 86% (n = 1660) at age 5 years for children with affected siblings. MMR vaccine receipt was not associated with an increased risk of ASD at any age. For children with older siblings with ASD, at age 2, the adjusted relative risk (RR) of ASD for 1 dose of MMR vaccine vs no vaccine was 0.76 (95% CI, 0.49-1.18; P = .22), and at age 5, the RR of ASD for 2 doses compared with no vaccine was 0.56 (95% CI, 0.31-1.01; P = .052). For children whose older siblings did not have ASD, at age 2, the adjusted RR of ASD for 1 dose was 0.91 (95% CI, 0.67-1.20; P = .50) and at age 5, the RR of ASD for 2 doses was 1.12 (95% CI, 0.78-1.59; P = .55). CONCLUSIONS AND RELEVANCE: In this large sample of privately insured children with older siblings, receipt of the MMR vaccine was not associated with increased risk of ASD, regardless of whether older siblings had ASD. These findings indicate no harmful association between MMR vaccine receipt and ASD even among children already at higher risk for ASD.

Does a claims diagnosis of autism mean a true case?

The purpose of this study was to validate autism spectrum disorder cases identified through claims-based case identification algorithms against a clinical review of medical charts. Charts were reviewed for 432 children who fell into one of the three following groups: (a) more than or equal to two claims with an autism spectrum disorder diagnosis code (n = 182), (b) one claim with an autism spectrum disorder diagnosis code (n = 190), and (c) those who had no claims for autism spectrum disorder but had claims for other developmental or neurological conditions (n = 60). The algorithm-based diagnoses were compared with documented autism spectrum disorders in the medical charts. The algorithm requiring more than or equal to two claims for autism spectrum disorder generated a positive predictive value of 87.4%, which suggests that such an algorithm is a valid means to identify true autism spectrum disorder cases in claims data.

Injuries among children with autism spectrum disorder.

OBJECTIVE: We compared risk of injury among children with autism spectrum disorder (ASD) to those without ASD, adjusting for demographic and clinical characteristics. METHODS: We used claims data from 2001 to 2009 from a commercial health plan in the United States. A validated ASD case identification algorithm identified 33,565 children (ages 0-20 years) with ASD and 138,876 children without. Counting process models tested the association between ASD status and injury episodes with separate regressions run for children during different age periods. RESULTS: Unadjusted results demonstrated that children with ASD had a 12% greater injury risk than children without ASD (hazard ratio [HR] = 1.119; P < .001). After including demographic variables, the HR was 1.03 (P < .05); after controlling for co-occurring conditions, such as seizures, depression, etc, HR decreased to 0.889 (P < .001). For the age period analysis, HR values were as follows: for 0 to 2 years, HR 1.141; 3 to 5 years, HR 1.282; 6 to 10 years, HR not significant; and 11 to 20 years, HR 0.634 (P < .05 for all significant results). CONCLUSIONS: Children with ASD have more injuries than children without ASD. After controlling for demographic factors and co-occurring conditions, children with ASD are at lower risk of injury, suggesting that co-occurring conditions or the ways these conditions interact with ASD is related to injuries. Clinicians should understand that injury risk in children with ASD may be driven by co-occurring conditions. Treating these conditions could thus decrease injury risk as well as have other benefits. Injury prevention interventions are especially warranted for younger children with ASD and those with seizures, depression, visual impairment, or attention-deficit disorders.