Child and Family Characteristics That Affect the Clinical Utility of the Modified Checklist for Autism in Toddlers As a Level II Screening Tool in Singapore

Background: The Modified Checklist for Autism in Toddlers (M-CHAT) is a 23 item parent questionnaire that was developed in the United States, to screen for Autism Spectrum Disorders (ASD) in 16-30 month olds. The M-CHAT is being used as a level II screening tool for developmentally at-risk children up to 48 months old, at a child development specialist clinic in Singapore. The M-CHAT has shown good clinical utility for the Singaporean high risk sample (Koh et al., in preparation). With the 18-30 month olds, the critical (failing 2/6 selected items) and Best7 (failing 2/7 selected items) scoring methods, detected a good majority of children with ASD, without inflating the false positive rate. With the >30-48 month olds, the non-critical (failing 3/23 items) scoring method was more accurate and less likely to miss those with ASD.

Objectives: This study examined the clinical utility of the M-CHAT by investigating child and family characteristics that may affect accuracy of the M-CHAT screening results.

Methods: Parents/caregivers of new patients were asked to complete an intake questionnaire, which included the M-CHAT, before their child’s first evaluation by a paediatrician. Medical records of 18-48 month olds seen between February 2009 and July 2010, whose parents/caregivers completed the M-CHAT (N=580), were reviewed. Children suspected to have ASD were referred for an ASD diagnostic assessment. For the children who received a diagnosis of ASD (N=198), Mann-Whitney and Chi-squared analyses were conducted to determine if there were significant differences between those identified accurately by the M-CHAT and those who were not, on i) measures of ASD severity and overall adaptive functioning of the child; and ii) family characteristics (such as educational level of parents). For the children who were not diagnosed with ASD (N=382), logistic regression analyses were conducted to determine if family characteristics predicted the accuracy of the M-CHAT results.

Results: The children with ASD who were identified accurately on the M-CHAT, had significantly higher ASD severity (non-critical:U=535.5, p=0.001; critical:U=780.0, p<0.001; Best7:U=825.5,p<0.001) and lower overall adaptive functioning (non-critical:U=372.0, p<0.001; critical:U=963.5, p<0.001; Best7:U=858.0, p<0.001), than those who were not. There were no significant group differences in family characteristics for the children with ASD. For the children without ASD, lower educational level of the parents was associated with more false positives on the M-CHAT than true negatives when using the non-critical scoring method (p=0.001).

Conclusions: The children with more severe ASD symptomatology and lower overall adaptive functioning are more likely to be detected on the M-CHAT. The accuracy of the M-CHAT for detecting children with ASD appears to be unaffected by demographic characteristics of the children’s parents. For the children without ASD, there were higher false positive rates when parents of lower educational levels completed the M-CHAT. These parents may have poorer understanding of the questions on the M-CHAT or of the importance of observing early social and communication behaviours in their young children. Parents may need to be better educated on child development, so that they can be better aware of typical versus atypical early development in their children.