New DSM-5 Severity Level Ratings for Autism Spectrum Disorder: Clinical Use and Associated Factors

Background:

The newest edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) introduced substantial changes to the criteria for autism. The shift from separate diagnostic subcategories into a single category of autism spectrum disorder (ASD) resulted in considerable discussion and research. By contrast, the introduction of new severity level ratings for social communication and restricted and repetitive behavior (RRB) in DSM-5 has received little scientific attention. Although the ratings intended to capture domain-specific severity, clear-cut operational definitions are lacking. Thus, it is unclear how these rating will be used and whether they will reflect symptom severity alone or be influenced by other indices of impairment.

Objectives:

The study objectives were to evaluate the use of DSM-5 severity level ratings in a large sample of children with ASD and to examine their relation to standardized measures of ASD severity and other clinical features, particularly cognitive and behavioral functioning.

Methods:

Participants included 248 children and adolescents with ASD (ages 2-17, 82% male) who received comprehensive diagnostic evaluations for autism at one of six Autism Treatment Network sites. Each assessment included a review of records, diagnostic clinical interview, Autism Diagnostic Observation Schedule – 2nd Edition (ADOS-2), cognitive assessment, assessment of behavioral functioning (Child Behavior Checklist, CBCL, and Aberrant Behavior Checklist, ABC), and completion of a DSM-5 Checklist.

Results:

Twenty-six percent of the sample was rated as having the lowest severity (Level 1, “requiring support”) in both domains, while 15% was rated as having the highest severity (Level 3, “requiring very substantial support”) in both domains. Bivariate analyses (cumulative logistic regression for the three levels of severity, binary logistic regression for lowest severity, and linear regression) all indicated that higher severity ratings in both domains were significantly associated with younger age, lower IQ, and greater ADOS-2 domain-specific symptom severity (p < .05 for all). The strength of associations was moderate/large for age (Spearman’s correlations of r_s = -.51 and -.43) and IQ (r_s = -.61 and -.47), and small for ADOS-2 domains (r_s = .23 and .29). Greater DSM-5 RRB severity was also associated with higher parent-reported stereotyped behaviors (measured by the ABC) in two of three bivariate models. Severity ratings were not associated with emotional or behavioral problems (measured by the CBCL). Multiple regression models indicated that age, IQ, and ADOS-2 social affect were significant independent predictors of social communication severity (p < .05 across all models), and that age, IQ, and ADOS-2 RRB were significant independent predictors of DSM-5 RRB severity (p < .05 across all models).

Conclusions:

These findings partially support the concurrent and discriminant validity of the new DSM-5 severity ratings. Clinician ratings of severity in both domains were significantly associated with behavioral observations of autism severity, but not with measures of other behavioral or emotional symptoms. However, the strong associations between IQ and DSM-5 severity ratings in both domains may suggest that clinicians are including cognitive functioning in their overall determination of symptom severity. Further research is needed to examine clinician decision-making and interpretation of these specifiers.