Preliminary Analysis of the Function of Self Injurious Behavior in the Autism Inpatient Collection (AIC) Sample

Background:  The functions of self-injurious behavior (SIB) have been under-examined in samples of youth with autism spectrum disorder (ASD) with the full range of intellectual functioning and verbal ability.

Objectives:  The Autism Inpatient Collection (AIC) was developed as a resource for the study of the full autism spectrum.  Data regarding the occurrence and function of SIB was collected through parent and staff report measures and clinician assessments.

Methods:  Youth aged 4-20 years, with an ADOS-confirmed autism diagnosis and admitted to a specialized inpatient psychiatry unit, were prospectively enrolled in a six-site study examining patient phenotypes, including SIB.  Participants screened positive for SIB with a two or greater at admission on any item of the parent-reported Repetitive Behavior Scale – Revised, Self- Injury Subscale.  For screen positives, the parent also completed the Functional Analysis Screening Tool (FAST) to examine the function of the SIB (i.e., attention, escape, sensory stimulation, or pain attenuation).  An inpatient staff member also completed a FAST on subjects who displayed at least daily SIB.  Intra-class correlation (ICC) analysis was conducted to examine agreement between parent and staff FAST measures.  For subjects with both parent and staff FAST completed, the unit behavioral specialist (behavioral psychologist or BCBA) utilized that data and their own extensive observations to make a final determination of the primary function of the patient’s SIB.  

Results:  Mean age of the first 108 subjects was 12.70 years (SD=3.50), 24% female, 77.8% identified as Caucasian and 91.4% Non-Hispanic/Non-Latino.  Seventy-three percent of parents (n=79) reported the presence of SIB at admission, with the majority (59.2%) reporting daily occurrence.  On the FAST, parents ranked attention (45.4%) as the most prominent function of SIB, followed by escape (28.8%), sensory (22.8%), and pain (3%).  For patients who exhibited SIB at least daily, staff ranked escape (45.5%) as the most prominent function of SIB on the FAST, followed by attention (31.8%), sensory (22.7%), and pain (0%).  Level of absolute agreement between parent and staff FAST scores was very low, attention (ICC=0.12, p=0.24), escape (ICC=0.12, p=0.26), sensory (ICC=-0.48, p=0.86), and pain (ICC=0.07, p=0.35).  Finally, the unit behavioral specialist reported 26.9% (n=29) of the overall patient population to engage in SIB, and noted multiple functions were present for most patients: escape (97%), attention (93%), sensory (83%) or pain (58%).  Using all available information, the behavioral specialist ranked escape as the primary function most frequently, followed by attention, sensory stimulation and pain attenuation.  

Conclusions:  Preliminary data suggests that 26.9% of children in the Autism Inpatient Collection engage in SIB at least daily, which is most commonly related to an escape function, followed by attention, sensory stimulation, or pain attenuation, as determined by the unit behavioral specialist. There was poor inter-rater agreement between parents and staff on the FAST, which could reflect differences in parent and staff observations or the function of the SIB changing across home and the inpatient setting.  Future analyses will examine the impact of verbal ability, IQ and other factors on the presence and function of SIB in this rigorously characterized sample.