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Stability of Sensory Subtype One Year Following Diagnosis of Autism Spectrum Disorder
Distinct patterns of sensory features, known as sensory subtypes, have been identified in children with Autism Spectrum Disorder (ASD; Ausderau et al, 2014; Lane et al, 2014). Both studies - conducted independently and using different measurement tools - conclude that sensory features in ASD vary based on the severity of parent-reported symptoms, the nature of the sensory response and the sensory modalities affected. Taken together, the findings of these studies suggest that sensory subtypes may provide a profitable method of identifying clinically meaningful ASD phenotypes. The stability over time of classifications made on the basis of sensory subtype, however, has only been examined in a longitudinal design in a single cohort of individuals with ASD who were at varying points along their care pathways (Ausderau et al, 2014). While this study found that subtype membership was stable over time, previous cross-sectional research has suggested that sensory symptoms tend to become less severe with age. Further longitudinal analysis of change in sensory symptoms is warranted particularly as it relates to participation in therapy. Sensory features are a primary target for autism-specific interventions and, therefore, may be expected to vary in presentation as a function of length of time in therapy.
Objectives:
The purpose of this study was to examine the stability of sensory subtype classification one year immediately following ASD diagnosis. We hypothesized that in one-year following diagnosis, sensory symptoms would be less severe than that reported at diagnosis.
Methods:
Participants (n=62) were children aged 2-10 years presenting to a major, Midwestern autism specialist center for diagnostic assessment between 2008 and 2010. All participants were administered the Short Sensory Profile (SSP) at diagnosis. This tool assesses parent-report of sensory symptoms from which sensory subtypes can be derived (Lane et al, 2014). One year following diagnosis, the SSP was re-administered. Participants were assigned to one of four sensory subtypes at each assessment point: 1) Sensory Adaptive, 2) Taste Smell Sensitive, 3) Postural Inattentive, or 4) Generalized Sensory Difference. A further classification of sensory symptom severity was made. Specifically, ‘mild’ severity comprised members of Sensory Adaptive; ‘moderate’ severity comprised members of Taste Smell Sensitive and Postural Inattentive; and ‘severe’ severity comprised members of Generalised Sensory Difference. We assessed the agreement in classification of sensory subtype and sensory severity between diagnosis and one-year follow-up using the Kappa statistic with 95% confidence intervals.
Results:
There was little evidence of change in sensory subtype classification from diagnosis to one-year follow-up (65% of participants remained in the same subtype; Kappa = 0.51, 95% CI: 0.34, 0.67). Further, most participants did not change sensory severity classification from diagnosis to one-year follow up (74% of participants remained in the same severity category; weighted Kappa = 0.52, 95% CI: 0.32, 0.72).
Conclusions:
The findings of this study suggest that sensory subtype as measured by parent-report is stable one-year following diagnosis. We did not observe significant abatement in sensory symptom severity in this timeframe.