Introduction The use of emergency services among adolescents and adults with autism spectrum disorder (ASD) transitioning into adult health services has not been well described.

Objectives To describe emergency service use including emergency departments (EDs), paramedics, and police involvement among adolescents and adults with ASD and to examine predictors of using emergency services.

Methods Caregivers of 396 adolescents and adults with ASD were recruited through autism advocacy agencies and support programmes in Ontario to complete a survey about their child's health service use. Surveys were completed online, by mail and over the phone between December 2010 and October 2012. Parents were asked to describe their child's emergency service use and provide information about potential predictive factors including predisposing, enabling and clinical need variables.

Results According to parents, 13% of their children with ASD used at least one emergency service in a 2-month period. Sedation or restraints were used 23% of the time. A combination of need and enabling variables predicted emergency service use with previous ED use in the last year (OR 3.4, 95% CI 1.7 to 6.8), a history of hurting others (OR 2.3, 95% 1.2 CI to 4.7) and having no structured daytime activities (OR 3.2, 95% CI 1.4 to 7.0) being the strongest multivariate predictors in the model.

Conclusions Patients with ASD and their families are likely to engage with paramedics or police or visit the ED. Further education and support to families and emergency clinicians are needed to improve and, when possible, prevent such occurrences.