Sex Differences in Presenting Concerns and ASD Diagnostic Outcome in a Clinical Sample

Background: According to the Center for Disease Control and Prevention, approximately 1 in 68 children have been identified with autism spectrum disorder (ASD). There is a higher rate of ASD diagnosis in males than females. ASD is characterized by qualitative deficits in areas of reciprocal social interaction, verbal and non-verbal communication, and the presence of repetitive, stereotyped behaviors and interests. However, males and females have been found to manifest these core symptoms differently. One of the key research priorities in autism research is the identification of early biological and behavioral indicators of ASD; at present, the influence of sex differences on clinical identification and diagnosis of children with ASD is poorly understood.

Objectives: To examine relationships among sex differences in identification of developmental concerns, ASD assessment results, and diagnosis in a sample of patients at a clinic specializing in developmental disorders.

Methods: The study sample included 34 children (26 males:6 females, aged 8+/-3 and 9+/-5, respectively; t(30)=0.67, p=.51]) referred to a specialty autism clinic within a two year period; data collection and retrospective analyses of additional historical cases are ongoing. All children were administered the Autism Diagnostic Observation Schedule (ADOS). Chi-square statistics were used to evaluate the likelihood of children meeting ADOS criteria for ASD as a function of sex. T-tests compared sexes in terms of age at which parents were concerned and initially sought help. Qualitative chart review examined differences in the nature of parents’ concerns, clinical profiles, and diagnostic outcomes by sex.

Results: Girls and boys did not differ in age of first parental concerns (Male: 24.56+/-22.65 months; Female: 21.80+/-14.87 months; t(28)=0.26, p=.80) or age at which parents sought professional consultation (Male: 32.14+/-25.13 months; Female: 25.60+/-20.01 months; t(25)=0.54, p=.59). Despite these similarities, girls were significantly less likely to meet criteria for ASD on the ADOS (χ2 =11.13, p=.003) during their clinic visit. Whereas 81.3% of boys met ADOS criteria for ASD, this was true of only 16.7% of girls. Qualitative chart review indicated parents’ first concerns were similar for boys and girls (e.g., speech, social difficulties, atypical behaviors). Among the girls, 2 were given ASD diagnoses, 1 of whom received an ASD diagnosis despite not meeting ADOS criteria. Alternative diagnosis given to girls included Attention Deficit Hyperactivity Disorder, and description of anxiety, nonverbal learning profile, as well as no diagnosis.

Conclusions: Sex differences were not evident in when parents began to have concerns about their child and when they first brought their concerns to a professional. However, with respect to the identification and diagnosis of ASD, it was found that girls were significantly less likely to meet criteria on the ADOS. These data suggest a discrepancy in the identification between males and females and are consistent with the idea that females may be less likely to get an ASD diagnosis based on conventional diagnostic procedures.