A fundamental component of pediatric practice is parent appraisal of child development.1
Developmental history taking, including elicitation of parental concerns, is standard in most routine pediatric visits and is used to alert physicians to the possibility of conditions requiring further evaluation. As the incidence of and media attention to autism spectrum disorders (ASD) increase, concerns about the possibility of these conditions are increasingly being raised by parents.2
Recently published guidelines from the American Academy of Pediatrics recommend that pediatricians ask parents about developmental concerns at each well-child visit and screen all children for autism twice by the second birthday.3
If concerns are identified by parents, the American Academy of Pediatrics' surveillance and screening algorithm3
recommends that an autism-specific screener should be administered and/or the child should be referred for a diagnostic evaluation, depending on the level of concern. Thus, parent report alone can trigger a referral for further evaluation.
Retrospective studies indicate that parents recognize signs of autism far earlier than it is diagnosed. Although symptoms are typically present by the second birthday and one third of parents cite concerns before the first birthday,4
diagnoses are often not made until the fourth year of life or later.5
Early concerns are sometimes dismissed,2
resulting in a several month to several year delay of diagnosis.6–8
Thus, early detection methods need improvement, in the hope that earlier diagnosis will lead to earlier initiation of treatment and reduced disability. As reviewed below, there is a robust literature on the accuracy of parent reports in general and for predicting developmental delays specifically; little, however, is known about their utility in predicting later autism diagnoses.
Several studies have examined how well parent information corresponds with developmental tests and/or expert clinical judgment. Correlations are moderately high (0.45– 0.65) between parent report of vocabulary and concurrent expressive language scores9
and very strong (0.80) between parent estimation of their child's developmental age and actual developmental quotients obtained through standardized testing.10
Parent concerns in high-risk infants were confirmed by formal assessment 95% of the time.11
Glascoe and colleagues12
have standardized the measurement of parent concerns through an instrument, the Parents' Evaluation of Developmental Status (PEDS). It is designed for children birth to 8 years and asks both general questions about concerns (please list any concerns about your child's learning, behavior, or development) and specific questions about concerns in 10 individuals domains (i.e., cognitive, language, motor, self-help). The Parents' Evaluation of Developmental Status demonstrates high accuracy in predicting disability (sensitivity 0.79 and specificity 0.72 in a sample aged 21 to 84 months).13
Although the Parents' Evaluation of Developmental Status was developed as a broadband screening instrument, a recent investigation found that parent concerns recorded between 18 and 59 months were correlated with concurrent scores on the Modified Checklist for Autism in Toddlers,14
suggesting that it might be useful to screen for ASD as well. This finding was not replicated in a study screening 18- to 30-month old infants in primary care settings,15
however, leading these authors to suggest that ASD-specific tools will be needed in the universal screening process.
However, the importance of assessing the accuracy of parent reports of early development and their predictive validity for identifying autism is complicated in several ways. Several studies suggest that signs of autism emerge gradually over time and that the earliest symptoms are subtle and not easy to detect, particularly by untrained observers.16
A few retrospective studies suggest that symptoms can be detected before the first birthday in some children,17,18
but these early differences appear to be nonspecific (e.g., sleeping, eating, temperament patterns) and do not differentiate children with developmental delays from those with autism.19
Group differences are more reliably present and consistently found across studies in the second year of life.20
Several prospective investigations of infants at higher risk for autism (because of family history) have failed to find differences at 6 months between children who are later diagnosed with autism and those who develop typically.21–24
Bryson et al,25
in a consecutive case series of infant siblings who developed autism, followed prospectively from 6 months, describe several children whose symptoms are not present at their 6- and 12-month visits but emerge slowly during the second year of life. Not a single child who developed autism (n = 9) displayed marked limitations in social reciprocity at 6 months. All 9 infants were described as interested in social interactions, responsive to others, demonstrating sustained eye contact and social smiles. This pattern of slow emergence of symptoms during the first year and a half of life may complicate efforts to use parent reports to identify autism symptoms earlier.
A second complication is the influence of risk status on parent reporting. Several studies have demonstrated that parents' perceptions of child development are impacted by their child's health status. For example, low birth weight children were rated as in poor health significantly more commonly by parents than by professionals.26
In prospective studies that follow high-risk families who already have a child with autism, as in this investigation, it is possible that parents may have heightened vigilance to developmental variations and over-report concerns. Conversely, it is equally possible that such parents will be more astute observers of child development who notice subtle manifestations of early developmental problems that may not yet be apparent on standardized assessments. Studies have shown that typically developing children whose parents reported concerns but who passed developmental screens (apparent false positives) performed significantly lower on tests of cognitive functioning and had significantly more behavioral problems than children whose parents raised no concerns.27
It was concluded that parents who appeared to be excessively worried were in fact “… vigilant observers who noticed behavioral and developmental problems that fall in the gray zone between disabled and average.”27(p. 6)
Parent concerns have also been found to correlate with developmental test scores in toddlers at risk for autism.28
This study collected parent concerns about development for infants at high and low risk for autism, using a prospective, longitudinal design. Parents were asked about developmental concerns at study intake and when their infant was 6, 12, and 18 months. Infants were then followed up until 36 months, when diagnostic status was determined. We examined whether the number and type of parent concerns differed over time as a function of outcome status. Although previous studies have examined the ability of parent concerns to predict concurrent test scores in children at risk for autism,14,28
this study is the first to examine the relationship between longitudinal parent report and later diagnostic outcome.