Screening Versus Surveillance: Differences in Demographic, Developmental, and ASD Symptom Profiles

Background: The increasing prevalence of Autism Spectrum Disorder (ASD) has resulted in greater awareness and stressed the importance of ASD specific screening and surveillance. African-American children are less likely to be referred by pediatricians, and are diagnosed as much as 2 years later than Caucasian peers. Additionally, it has been shown that many primary care physicians do not engage in routine ASD screening. As early intervention improves the prognosis for children with ASD, it is important to address the gap in referral and diagnosis for children from minority backgrounds. It is also important to examine how surveillance and screening may differ in utility.

Objectives: We investigated the demographic, developmental, and ASD symptom profiles of children who are referred for ASD evaluation based on screening positive on the Modified Checklist for Autism in Toddlers (Revised; M-CHAT-R) compared to those who screened negative, but whose pediatrician had ASD concerns based on surveillance. Minority children, or children from lower SES, may be less likely to be referred for ASD by their pediatrician. Additionally, children caught through surveillance may show more severe symptom presentation than those detected through screening, and those detected by both would have the most severe symptoms.   

Methods: In our study, participating pediatricians distributed the M-CHAT(-R) during 18- and 24-month well-child visits (screening) and indicated whether they have concerns about the child’s development (surveillance). Developmental and ASD symptom profiles were examined for 208 children at risk for ASD: 155 from screening alone (SCR), 24 from surveillance alone (SURV), and 29 from both screening and surveillance (S+S). Evaluations consisted of measures of ASD symptomatology, general cognitive skills, and adaptive abilities.

Results: On measures of ASD symptomatology, children identified by S+S were more severe (CARS total score: M=32.05 SD=5.73; ADOS severity score: M=5.79, SD=2.48) than those identified by SCR (CARS total score: M=26.78 SD=6.86, p=.001; ADOS severity score: M=3.95 SD=2.53, p=.001); differences between S+S and SURV were not significant (ps>.056).

On cognitive, language, and adaptive measures, children detected by S+S (VABS Communication: M=75.59  SD=4.14; VABS Socialization: M=81.52  SD=10.02; MSEL Receptive Language: M= 25.62 SD=10.06) were more impaired than those detected by SURV (VABS Communication: M=86.63  SD=11.36, p=.011; VABS Socialization: M=89.54  SD=12.43, p=.018; MSEL Receptive Language: M=35.04  SD=14.51, p= .021). Additionally, on measures of socialization, children detected by SCR (VABS Socialization: M=83.28 SD=10.21) were more impaired than those detected by SURV (p=.021).

Children identified through S+S or SURV (n=53) had higher levels of maternal education (t(198)=3.32, p=.001) and were  more likely to be Caucasian (χ²(1,208)=4.61, p=.032) than those who were identified by SCR (n=155); however, Caucasian children were not more likely to be diagnosed with ASD than their African-American peers (χ²(1,208)=.56, p=.46) and level of education did not differ significantly based on diagnosis (t(198)=1.79, p=.075).  

Conclusions: These results suggest that increased diagnosis among Caucasian and high SES families and later diagnosis of African-American children may be an artifact of differences in referral rates, not an actual difference in prevalence. Integrating screening and surveillance for the identification of ASD maximizes detection of children.