GENDER DIFFERNCES IN AUTISM SPECTRUM DISORDER CLASSIFICATION WITHIN A COMMUNITY BASED SAMPLE

Background: The widely accepted gender ratio in Autism Spectrum Disorders (ASDs) is approximately 4:1 (boys:girls). Recent studies suggest rates rangoing from 2.8:1 to 5.5:1 based on review of historical records and as high as 8:1 based on special education placement.

Objectives: To determine gender differences in ASD classification based on case definition and symptom presentation.

Methods: Participants included 197 children (ages 4-9) who participated in a larger prevalence study in south Florida. We examined the gender ratios obtained by applying different case definitions of ASD including: 1) parent-reported ASD diagnosis, 2) first diagnosis received, 3) score on SCQ and 4) historical record review. We also examined agreement between SCQ and record review classifications across gender.

Results: The male:female ratios for three case definitions were similar: 6.5:1 for parent-reported ASD diagnosis, 6.3:1 for ASD as first diagnosis and 6.8:1 for SCQ score. However, the ratio was much higher (8.1:1) using historical record review. The agreement between SCQ and record review classification was 75% for boys, but only 63% for girls.

Conclusions: Results indicate that gender ratios are affected by case definition and may be higher than previously reported. It may also be that girls are under-identified using certain criteria. In order to further explore these findings, we will also examine differences in symptom presentation, school eligibility and type and source of first diagnosis. Implications for policy and clinical practice will also be discussed.