Use of Home Videotapes to Confirm Parental Reports of Regression in Autism

Transcription

1 J Autism Dev Disord (2008) 38: DOI /s ORIGINAL PAPER Use of Home Videotapes to Confirm Parental Reports of Regression in Autism Wendy A. Goldberg Æ Kara L. Thorsen Æ Kathryn Osann Æ M. Anne Spence Published online: 5 December 2007 Ó Springer Science+Business Media, LLC 2007 Abstract The current study examined consistency between parental reports on early language development and behaviors in non-language domains and observercoded videotapes of young children with and without autism spectrum disorder (ASD) and autistic regression. Data are reported on 56 children (84% male) with ASD (early onset or autistic regression) and 14 typically developing children (57% male) who had home videotapes. Unique to the current study is the independent identification of loss/no loss for each child by both parental report and observer-coded home videotapes and the examination of agreement between these two methods. Results indicate substantial concordance between parental report and observer codes for onset and loss of expressive language, but minimal concordance for loss in non-language domains, suggesting a need for supplementation of parental reports in these areas. Keywords Autism Regression Language Videotapes Parent report Methodology W. A. Goldberg (&) K. L. Thorsen Department of Psychology and Social Behavior, 3389 School of Social Ecology II, University of California, Irvine, Irvine, CA 92697, USA wendy.goldberg@uci.edu K. Osann Department of Medicine, University of California, Irvine, Irvine, CA, USA M. A. Spence Department of Pediatrics, University of California, Irvine, Irvine, CA, USA Introduction Parental reports are critical for the diagnosis of autistic disorder. Most diagnostic testing for autistic disorder occurs after infancy and early toddlerhood but before children can speak on their own behalf. Retrospective accounts of what did and did not occur in early development are integral to commonly used diagnostic measures such as the Autism Diagnostic Interview-Revised (ADI-R; Rutter et al. 2003) and the Childhood Autism Rating Scale (CARS; Schopler et al. 1980). Parental accounts of these early years raise the problem of disentangling age at onset from age at recognition (Volkmar et al. 1985), raising questions such as when did symptoms begin and when did parents realize that the child was not developing typically. Between 36% (Short and Schopler 1988) and 55% (Volkmar et al. 1985) of parents recognize problems in their child s first year. Unfortunately, those numbers suggest that either some parents do not recognize or seek help for problems until the child is 2 or 3 years old or older, or some pediatricians fail to follow up on parents concerns, or both. Either case leads to a protracted delay before the child is referred for further evaluation. By the time these children are evaluated, the period of active regression may have passed (Shinnar et al. 2001). In clinical practices and research, parental reports, obtained from interviews and/or paper and pencil measures, are not an uncommon means of identifying symptoms of autism and regression. Maternal perception and report have been used to identify the differences between children with autism who did not regress and those children who lost skills in verbal and non-verbal communication and social abilities (Davidovitch et al. 2000). Parental report has also been used to provide data on early language development of preschool children with

2 J Autism Dev Disord (2008) 38: autism spectrum disorder. In one study, language development was assessed using the MacArthur Communicative Development Inventory-Infant Form, a parent-completed questionnaire (Charman et al. 2003). In another study, a large collaborative project, the ADI-R, a parent interview and a follow-up telephone interview with parents were used to describe the acquisition and loss of social-communication milestones in children with autism spectrum disorders (ASD; Luyster et al. 2005). In these instances and others, researchers and clinicians are dependent upon parental reports. Are Parental Reports Accurate? The accuracy of parental report of language has received a fair amount of attention in research conducted with nonclinical and clinical samples. In general, reliability and validation studies of parental report measures indicate that parents can provide accurate information about a variety of developmental phenomena (Burgess et al. 1984; Kenny et al. 1987), but there is variation across and within studies. Parental reports of language and other domains of development correlate moderately well with children s skill assessments and observer judgment (Camaioni et al. 1991; Dale et al. 1989; Miller et al. 1995; Patterson 2000; Ring and Fenson 2000) Among typically-developing children, parental reports of children s early pattern of communicative and linguistic development are significantly and positively correlated with those reported by observers (Dale et al. 1989; Camaioni et al. 1991). Parental reports also significantly correspond with typically-developing children s performance on tasks measuring expressive and receptive vocabulary (Ring and Fenson 2000; Patterson 2000). The Language Development Survey, a screening device that uses parental report to measure children s expressive vocabulary, showed strong concurrent validity with several clinical language and developmental measures (Rescorla and Alley 2001), as well as excellent sensitivity and specificity for identifying language delay at age two (Klee et al. 1998). However, the Language Development Survey showed somewhat lower levels for predicting developmental status 1 year later (Klee et al. 1998). Parents have been shown to provide fairly accurate descriptions of language in children with developmental problems. Findings from studies of preschoolers with neurodevelopmental conditions (e.g., Down Syndrome) reflect generally moderate agreement between parental report and direct, formal test measures of vocabulary size (e.g., Miller et al. 1995). In addition, moderate consistency has been observed between parental and professional ratings of pragmatic aspects of communication difficulties for children with pervasive or specific developmental disorders (Bishop and Baird 2001). Moderate correspondence has been observed between parental accounts and professionally-assessed child functioning in cognitive skills other than language. Four out of five scale scores from the Minnesota Child Development Inventory, which uses parental reports, were positively and significantly associated with each of the six subscores on the McCarthy Scales of Child Development, a professionally administered psychological test that assesses verbal ability, perceptual-performance, quantitative ability, memory, motor skills, and yields a general cognitive index (Kenny et al. 1987). In areas other than language and cognition, a mixed picture emerges. The Play Activity Questionnaire, a parental reported play scale, yields four factors that showed significant small to moderate positive correlations with several measures of activity level, aggression, and sextyped play (Finegan et al. 1991). In another study, a moderate to high degree of concordance was found between parental reports of infants use of particular objects as sleep aids and observer coding of sleep aid use during a total of six all-night videotape sessions. Where discordance was evident, the error was on the side of the parents underreporting the use of sleep aids (Burnham et al. 2002). Studies examining correspondence between parent report measures of temperament and observer ratings have reported conflicting results. For example, parental report measures of temperament demonstrated moderate correspondence to observer ratings of temperament based on infant behavior in a laboratory situation (Bridges et al. 1993; Clarke-Stewart et al. 2000). However, in another study, there was little evidence of motherobserver correspondence on assessments of temperament (Seifer et al. 1994). Parental report has been relied upon as a major source of information about potential and actual problem behaviors and developmental delays. Asking parents about any concerns they may have about their child and having parents complete questionnaires related to child behavior and development are commonly-used methods to identify potential problem areas for children who do not yet have a current clinical diagnosis (Glascoe and Dworkin 1995). Maternal accounts of their children s psychopathology have been seen as one part of a reliable and accurate means of assessment of ADHD children (Faraone et al. 1995). In addition, maternal estimates provide an accurate measure of developmental functioning in children with suspected developmental delay. A high, positive correlation was found between maternal estimated developmental age and actual developmental age determined by standardized tests of cognitive functioning, adaptive abilities, expressive and

3 1138 J Autism Dev Disord (2008) 38: receptive language, and visual-motor skills (Pulsifer et al. 1994). The accuracy of parents retrospective accounts of various developmental milestones has received equivocal support. In one study, parental recall of first step and first word obtained retrospectively when the child was 3 and 5 years old were compared to original reports gathered when the child was 1 year of age. A strong, positive correlation was found between the age recalled and the actual age for independent walking. In contrast, only a weak correlation emerged between recalled age and actual age of first word (Majnemer and Rosenblatt 1994). Another study found that mothers knowledge about language development, although not perfect, was stronger than and unrelated to their knowledge about play. Thus, maternal knowledge about developmental domains may be differentiated and domain-specific (Tamis-LeMonda et al. 1998). Use of Home Videotapes Recently, researchers have included observer-coded videotapes as a primary method of assessing characteristics of ASD. Retrospective home videotapes are considered to be less affected by time or distortion of recall of early events than are parental reports. Using retrospective home videotape analysis, researchers have found that children with ASD and typically developing children differ in the frequency of responding to name calls (Baranek 1999; Osterling and Dawson 1994; Osterling et al. 2002), stereotypic motor behaviors (Adrien et al. 1993; Baranek 1999), gazing at others (Adrien et al. 1993; Maestro et al. 2002; Osterling and Dawson 1994; Osterling et al. 2002; Werner et al. 2000), and smiling at others (Adrien et al. 1993; Maestro et al. 2002). Retrospective home videotapes have also been used to validate parental reports of the phenomena of regression in autism. Werner and Munson (2001) validated a new parental report method, the Early Development Interview (EDI), using home videotapes. The EDI was found to consistently describe characteristics of regression, such as the loss of social and communication skills (Werner and Munson 2001). Werner and Dawson (2005) observed differences in patterns of behavior on home videotapes for groups determined to have early autism, autistic regression, or typical development by parental report. The difference found between the patterns of development in these groups of children validates the parental reported phenomenon of regression in autism, but the authors did not directly compare the concordance between parental report and observer coded home videotapes. The Current Study In prior research, parental reports have been used to identify typical and atypical development of language and other domains in children with autism and moderate correspondence is common, with some variation by domain and study. The accuracy of parent report remains to be directly compared to observer ratings for children with regression and early onset forms of autism. Given the pivotal roles played by videotape data and parental reports in the study of autism and other developmental phenomena, a direct comparison of these approaches is needed. In the current study, we examine the extent of consistency between parents retrospective reports of age of expressive language onset, loss of expressive language, and loss in other non-language areas and observer-ratings of home videotapes of children s behavior during the early years. Based on studies that have compared parental accounts and observational data in clinical and non-clinical samples, moderate concordance was expected with respect to parental reports of language regression and observercoded home videotapes. Less strong, but still significant, consistency was expected for all non-language domains. Method Participants The sample consisted of 56 children (84% male) with ASD and 14 typically developing children (57% male), the majority of whom were Caucasian. Children were 5 years old on average (SD about 2 years for children with and without ASD) when seen for diagnosis and neuropsychoeducational assessment at the medical center of a large research university in the western United States. Children were recruited as part of a large, federally-funded study of the neurobiology and genetics of autism with a specific focus on regression. Typically developing children who had early home videotapes and the autism assessment battery were a subsample of a larger pool of non-affected children recruited for the study. Families provided videotapes filmed at first and second birthday parties, as well as home videotapes from non-birthday occasions that were age-matched to the birthday party tapes. Non-birthday party tape also was collected for 6 and 18 months, thus producing videotape for coding at four data points; 6, 12, 18, and 24 months of age. Two children were excluded from consistency analyses; one child with ASD was excluded due to missing information on the ADI and one typically developing child was excluded because a sibling was

4 J Autism Dev Disord (2008) 38: Table 1 Sample descriptives for children with ASD and typical development (TD) ASD TD N % N % Gender Male Female Ethnicity Caucasian Asian Other/mixed Unknown ASD TD N M (SD) Range N M (SD) Range Age at testing (year) (2.31) (1.94) IQ total (24.24) (15.04) Stanford-Binet (21.45) (15.04) Mullen (16.64) IQ verbal (25.41) (19.53) Stanford-Binet (21.45) (19.53) Mullen (15.93) IQ non-verbal (25.09) (5.32) Stanford-Binet (21.01) (5.32) Mullen (20.53) PPVT (23.60) (16.80) diagnosed with ASD. For other analyses, occasional missing or non-informative tapes reduced the actual sample sizes for some comparisons. Table 1 provides descriptive information on the final study sample. Procedure At the first visit to the medical center, parents were interviewed by trained clinicians using the Autism Diagnostic Interview- Revised (ADI-R; Rutter et al. 2003) and Autism Diagnostic Observation Schedule-Generic (ADOS-G; Lord et al. 1989). Scores were reviewed and diagnoses confirmed in weekly case meetings conducted by a licensed clinical psychologist. The Regression Supplement Form (RSF; Goldberg et al. 2003) was completed by parents either by mail or phone. Children were also administered a battery of tests of intellectual/cognitive ability and linguistic functioning. Home videotapes made during the first 2 years of the child s life were delivered to the medical center when children came for testing; copies were made for later coding and original tapes were returned to the families. Measures Intelligence Testing IQ for each child was assessed using one or more of the following measures: Stanford-Binet Fifth Edition (SB-FE), the Mullen Scales of Early Learning (MSEL), and the Peabody Picture Vocabulary Test (PPVT). The MSEL was administered to children below with a mental age younger than 2 years of age. The PPVT was given to some children as a proxy measure of verbal IQ. Parental Report: Autism Diagnostic Interview-Revised (Rutter et al. 2003) This assessment is a standardized, semi-structured interview, approximately 90 min long, conducted with caregivers of children with autistic disorder. It includes questions about the child s family, schooling, developmental history, and behaviors commonly associated with autistic disorder. The interview yields detailed descriptions of behaviors to inform a diagnosis of autism and related

5 1140 J Autism Dev Disord (2008) 38: disorders. The ADI-R also includes a battery of questions pertaining to the loss of skills in several domains (e.g., communication, social interest and responsiveness, play and imagination). It was used in the present study for diagnosis and to obtain data on whether losses occurred during the early years and the domains of loss. Parental Report: Regression Supplement Form (Goldberg et al. 2003) The RSF probes for type of loss, timing of loss, and possible regain of 18 specific skills and was designed for use with parents of children who have regression in autism. Consistent with the ADI-R, the skills represent the domains of spoken language, non-verbal communication, social interest and responsiveness, and play and imagination. The RSF has been shown to have good inter-coder reliability (91%) and validity (Goldberg et al. 2003). It was used in the current study to determine age at loss and duration of losses in language and other domains. Observer Coding of Behaviors Home videotapes were coded using a coding scheme developed by Osterling and Dawson (1994) and adapted for the current study with permission of the authors. Videotape data consisted of the frequency of discrete behaviors and skills captured on tape at 6, 12, 18, and 24 months and video codes that indicated the quality of each frame. Behaviors of interest included those related to language and ranged from the frequency of pre-verbal vocalizations and babbling to the frequency of single, meaningful words and multiple words. Non-language behaviors of interest included non-verbal communication (e.g., pointing, showing objects to another, nonverbal pragmatics), social behaviors (e.g., joint reciprocal social activity, initiating social bid), gaze (e.g., looking at the face of another, alternating gaze between object and person), orienting to name calls (e.g., responds with a head turn within 3 s to name being called), and play (manipulates objects, relational and functional play with objects, symbolic play). Variables also were coded from videotapes that pertained to the quality of video and audio on tape and the context in which the child was situated. These video codes included the length of footage, number of children and number of adults on screen, the setting (outdoors or indoors), whether the child s face is in clear view, and whether the child was free to move around or was motorically restrained. Research assistants who were blind to diagnostic group and who did not code the tapes were responsible for editing a minimum of three minutes and up to 15 min of data with the child on screen for each birthday and non-birthday videotape at each age. Tape length averaged nine minutes (SD = 4.2) for the ASD children and 11.5 min (SD = 4.0) for typically developing children. Using time/date stamps on the videotape when available (or holidays and birthday parties when not available), editors started with the videotape footage that was closest to the targeted age (e.g., 12 months) to reach the goal of 15 min of tape with the child on screen. The number of usable videotapes at each age (6, 12, 18, 24 months) ranged from 21 to 39 tapes (M = 29.0) for the ASD sample and from 7 to 9 tapes (M = 8.3) for the typically developing sample. Fewer tapes were available at 6 months than at other ages; tapes from this age were used primarily to inform presence or absence of vocalizations and babbling. Frequencies for the behaviors of interest were calculated as the number of behaviors divided by the minutes of tape available. When data were available for the birthday and non-birthday occasions at the same age, an average of the frequencies of behaviors was used. Tapes were coded by 2 4 trained research assistants who were blind to diagnostic category and who had received extensive training; inter-rater reliability exceeded 80% for total frequencies for each of the composite variables included in the analyses (e.g. social behavior). Determination of Consistency between Parental Report and Observer-Coded Videotapes During the ADI-R parent interview, parents were asked the age at which their children spoke their first word. Based on interview data, delayed onset was coded for those responses in which the parents reported that their children were older than 18 months of age at the time of their first word. Language loss was coded if parents reported definite loss of several words other than mama or dada and subsequent loss of those words on both the ADI-R and RSF. Parents who indicated possible or definite loss in two of the three categories of speech, words, or communication also were labeled possible loss and included in the language loss category. Parents who reported loss of a skill on the ADI-R answered additional questions from the RSF to determine the age at loss and duration of the loss. Based on the coding of the home videotapes, delayed onset of language was denoted for children who did not utter at least one single, meaningful word on any videotapes by 18 months. Language loss was coded for children who used words on tape at 12 or 18 months but who did not use words at 24 months, or for children who showed at least a 50% decline in babbling with increasing age without a corresponding increase in frequency of word use.

6 J Autism Dev Disord (2008) 38: Consistency in onset of language was affirmed when parents reported delayed onset of language (first words after 18 months) and the video coders concurred with the absence of spoken words on available videotape up to 24 months. Consistency was also noted when parents reported normal onset of language (defined as first words by 18 months) and the video coders concurred with the presence of spoken word on available videotape consistent with the parental-reported age of onset. Consistency in loss of language was coded when parents reported the loss of previously spontaneous words (as defined above) and the video coders observed either: (1) spoken words on early videotapes followed by absence of words during the time window in which parents reported loss, or (2) a decline of at least 50% in frequencies of expressive and pre-verbal language behaviors over time and loss of higher level language behavior. The adherence to the benchmark of a decline by 50% or more in frequencies of expressive language over time ensured a more objective interpretation of behavior and was intended to capture the process of regression, which is often reported to occur gradually rather than suddenly (Goldberg et al. 2003). Agreement between parents and observers also was coded if no words were spoken on the videotape during the time period of parental-reported loss, but words were spoken coincident with the time of parental-reported regain of language. Consistency in loss of other, non-language areas (such as gaze and social behavior) was coded when parents reported the loss of skills in any non-language area and the video coders also observed loss of skills in a non-language area. Specifically, to be termed consistent in reporting loss, the following criteria had to be met for each non-language area: (1) the behavior had to occur with a frequency greater than zero before the loss could be assigned, and (2) the frequency of the behavior had to drop by at least 50% to be considered loss. Plan of Analysis For data analysis, children were placed into one of three groups based on aforementioned diagnostic testing (e.g., ADI-R): typically developing, early autism, and autism with regression. For some analyses, the early autism and regression groups were combined into one ASD category. Consistency between parental report and observer coded home videotapes was measured by Cohen s kappa. Kappa indicates the degree of agreement beyond that which would be expected by chance (Cohen 1960). Interpretation of kappa values was guided by criteria set by Landis and Koch (1977): , Fair ; , Moderate ; , Substantial ; Almost perfect. The chi-square test was used to test for differences in the distribution of consistency or no consistency among the groups (typically developing children, children with ASD and no loss, and children with ASD and loss). Video codes for tape quality and several contextual variables were examined for their relevance for the findings of consistency between parental report of loss and observer codes on videotape using two-tailed t-tests with pooled variance. Results Language Onset Consistency in onset of language was affirmed when the video coders independently detected single words during a time that was consistent with the parental report on the ADI-R, and conversely, did not observe language before the age reported by parents. Consistency also was coded when parents reported delayed onset of language (i.e., first words after 18 months) and the video coders concurred with the absence of spoken words until that age. As shown in Table 2, consistency occurred significantly more frequently than inconsistency. Cohen s kappa was for agreement between parental report on the ADI-R and observer codes from home videotapes for typical language onset (B18 months) or delayed onset. Next, we examined consistency between the video codes and parental report on the ADI-R only for children with Table 2 Consistency between parental reports of language onset, language loss, and other losses and home videotape codes for all study children (ASD and TD) Observer codes from home videotapes Parental report from the Autism Diagnostic Interview-Revised (ADI-R) n (%) n (%) Variable Onset of language No delay Delayed onset No delay 19 (41.3) 1 (2.1) Delayed onset 7 (15.2) 19 (41.3) Cohen s kappa = Asymptotic standard error = Language loss No loss Loss No loss 25 (96.2) 3 (30.0) Loss 1 (3.8) 7 (70.0) Cohen s kappa = Asymptotic standard error = Other losses No loss Loss No loss 7 (26.9) 6 (30.0) Loss 19 (73.1) 14 (70.0) Cohen s kappa = Asymptotic standard error = 0.125

7 1142 J Autism Dev Disord (2008) 38: Table 3 Consistency in reports of language onset, language loss, and other losses on the ADI-R only for children with autism spectrum disorder (ASD) Consistency between video codes and parental report (ADI-R) n n Variable Language onset No delay Delayed onset Not consistent 6 2 Consistent v 2 (1) = 2.84; p \ 0.10 Language loss No loss Loss Not consistent 1 3 Consistent 17 6 v 2 (1) = 3.67; p \ 0.06 Other losses No loss Loss Not consistent 12 7 Consistent 6 12 v 2 (1) = 3.29; p \ 0.07 ASD. A trend-level difference among groups was found with more consistency when parents reported delayed onset of language and less consistency when parents reported no delay, as depicted in Table 3. (Parents of all typically developing children reported no language delay and were fully consistent with the video codes for typical onset of language and so these data were not included in these analyses.) Language Loss Next examined was the consistency between parents reports of language loss on the ADI-R and observers coding of language from the home videotapes for all study children (ASD and typically developing). Cohen s kappa was 0.705, for agreement between the parental reports and videotape codes (see Table 2). When analyses were restricted to ASD children only, findings of consistency or no consistency between parental report on the ADI-R and videotape codes for language loss approached significance (p =.055). Inspection of the data suggests that more consistency occurred when parents reported no loss of language (see Table 3). Parental reports obtained via the RSF were compared to observer ratings of the home videotapes within a smaller sample than available for the ADI-R. There was no agreement between the parental report and videotape for loss of five or more words (Cohen s kappa = 0.0, n = 10). Cohen s kappa was (n = 17) for agreement between parent report of loss of non-language skills and codes from home videotapes (see Table 4). Table 4 Consistency between parental report of language loss and other losses on the regression supplement form and home videotapes for children with ASD only Observer codes from home videotapes We examined whether the qualities of home videotape footage may have contributed to inconsistency between home videotape and parent report of language loss from the ADI-R. The consistent and non-consistent groups were compared on the contextual variables of tape length, tape quality, number of adults on screen, number of children on screen, number of name calls, and setting. Only the number of children on screen significantly differed between the groups in the direction of more children on screen for when parent reports and videotape codes were consistent, t(106) = , p \.02. Non-Language Losses Parental report from the Regression Supplement Form (RSF) n (%) n (%) Variable Language loss No loss Loss No loss 2 (40.0) 2 (40.0) Loss 3 (60.0) 3 (60.0) Cohen s kappa = 0.0 Asymptotic standard error = Other losses No loss Loss No loss 2 (66.6) 3 (21.4) Loss 1 (33.3) 11 (78.6) Cohen s kappa = Asymptotic standard error = We examined the consistency between parental reports of non-language loss on the ADI-R and non-language loss obtained through observers coding of early videotapes for both ASD and typically developing children. Cohen s kappa was , which indicated a lack of consistency between the observer codes and parental reports (see Table 2). An additional comparison of the distribution of consistency or no consistency within the ASD sample of children whose parents reported loss and no loss of nonlanguage behaviors revealed a significant difference between groups, such that a higher proportion of inconsistent findings occurred in the ASD sample of children whose parents reported no loss on the ADI-R than for children with ASD whose parents did report loss on the ADI-R (see Table 3). Cohen s kappa was for agreement between parental report from the RSF and observers coding of home videotapes for loss of non-language skills was (See Table 4). Non-overlapping confidence intervals indicate

8 J Autism Dev Disord (2008) 38: that the kappa for agreement between parent report on the RSF and observers coding of videotapes is larger than the kappa for agreement between parent report on the ADI-R and observers videotape codes for non-language skills. The consistent and non-consistent groups for non-language (other) losses were compared on the contextual variables of tape length, tape quality, number of adults on screen, number of children on screen, number of name calls, and setting. With one exception, context variables were not significantly related to consistency between parent report and videotape codes of other losses. Only the number of name calls significantly differed between the groups in the direction of more name calls when parent reports and videotape codes were consistent, t(138) = , p \.02. Discussion Until recently, parental reports have served as the sole means of obtaining information about autism and autistic regression in the first few years of life. Parental reports are easily obtained and commonly used, but are susceptible to subjective bias. Observer-coded videotapes, while free from parental bias, are themselves subject to questions of representativeness and generalizability, as well as reliability. To verify the accuracy of parental reports of language onset, language loss, and loss of other skills, we compared parental reports from a standardized diagnostic interview and supplemental questionnaire to observer codes from home videotapes of behavior during the very early years of the child s life. Results indicated more consistency for language losses than losses in other areas. This study refined and extended past research by investigating the onset of first words as well as examining loss in both expressive language and non-language domains for young children with early autism, autistic regression, and typical development. In addition to expressive language, domains of interest included nonverbal communication, gaze, social behaviors, orienting to name calls, and play, as these areas of development are critical to the diagnosis of autism and identification of autistic regression. Previous research investigating the phenomenon of autistic regression has confirmed loss of skills for children whose parents reported regression (Werner and Dawson 2005). Studies conducted with typically developing children have found moderate concordance between parental reports and observer judgments and assessment scores for many aspects of language (e.g. Camaioni et al. 1991; Dale et al. 1989; Ring and Fenson 2000). Prior studies have not always found substantial agreement between parental report and observer judgment for non-language areas of development such as play (Finegan et al. 1991); the current study examined consensus for several key domains of development in nonlanguage areas. Unique to the current study is the independent identification of loss/no loss for each child by both parental report and observer-coded home videotapes and the examination of agreement between these two methods in samples of children with and without ASD and autistic regression. Using Landis and Koch s (1977) interpretation of kappa, the results of the current study indicated substantial concordance between parental report from the ADI-R and observer codes from home videotapes for onset and loss of expressive language, but found an absence of concordance for losses in other domains of behavior. When parental reports on the ADI-R were compared to videotape data, parents were most accurate in detecting the onset of words and most consistent when reporting no loss than when claiming loss. Lower consistency between parental report from the ADI-R and observer codes from home videotapes for nonlanguage areas may be related to the level of detail of relevant questions on the ADI-R. This measure, although arguably the most reliable diagnostic tool for autism, asks about key domains in which there may be regression but does not include detailed questions and follow-up probes about the nature and course of regression in non-language areas. Also, interviewers who are attuned to autistic regression may be more likely than other interviewers to ask the probes that elicit the most complete information from parents. In addition to the ADI-R, the current study had another parent report measure, the RSF, to capture loss in language and non-language domains. The RSF asks parents about the nature and course of 18 specific behaviors that may have been lost (e.g. social smiling, spontaneous imitation of nontaught action, offers to share). The poor agreement between language loss as reported on the RSF and the videotape codes may have been an artifact of the small sample available for this analysis. However, results indicated that the RSF may be a useful supplement to the ADI-R as typically administered for non-language (other) losses in particular. The agreement between the RSF and videotape codes for non-language losses was fair, whereas there was virtually no agreement between the ADI-R and the videotape codes for non-language losses. The greater specificity for non-language behaviors on the RSF compared to the ADI-R may explain its better correspondence with the observer codes from the videotapes. The fact that the agreement even for the RSF was only fair may be due to the grouping of coded behaviors from the videotapes. In the current study, due to the number of cases, losses in several discrete non-language areas were not the unit of analysis; rather, frequencies of these behaviors were averaged and

9 1144 J Autism Dev Disord (2008) 38: analyzed as one category of behavior (e.g., joint reciprocal social activity and initiating social bid were components of the category social behaviors ). It might be prudent in future research to use a more discrete unit of analysis to examine whether certain types of non-language losses lend themselves to consistency more than others. If the divergent findings for types of losses are not an artifact of the current methods, they could indicate that maternal knowledge about developmental domains is differentiated and domain-specific (Tamis-LeMonda et al. 1998). In particular, the lack of consistency for non-language areas may have occurred because these losses are not as alarming (and therefore not as salient) to parents as is language loss (Luyster et al. 2005). Results from the current study suggest that when researchers and clinicians do not have home videotapes to verify parental reports, which will usually be the case, they can have confidence in the parents report of normal and delayed onset of language and in their reports of no loss in expressive language. This finding is especially critical when the focus is on ascertaining whether the timing of early language is normative or delayed and if a child has ASD without word loss. It is important that parents can be relied upon for reporting on their young children s language, as linguistic abilities are some of the best predictors of long-term outcomes for children with ASD; however, it is also necessary to assess the trajectory of development (and loss) in other, non-language areas, because these skills, too, are integral to development over the long-term (Sigman and McGovern 2005). By and large, contextual variables did not differ between consistent and non-consistent groups. An exception occurred for the number of children on screen when consistency in language loss was the focus. There was more consistency when there were more children on screen, which suggests that other children may elicit language, thus boosting the correspondence between parent report of no loss and children demonstrating language on the videotape. Having another child with the target child also may enhance recognition of no language, because having another child on screen when the child fails to speak highlights the absence of expressive language in the parent s mind and may contribute to consistency between parental report and videotapes. Another exception occurred for the number of name calls and consistency with parental report of other losses with more name calls when consistency occurred. However, because orient to name was one of the contributors to the other loss category and number of name calls was the denominator in creation of the orient to name variable, this redundancy could contribute to the significant finding. It is also possible that more frequent name calls by the parent provides more opportunity for coders to see other losses and also may make the child s responses, or lack thereof, more salient to the parent. In general, parents were more likely to report delays and losses in language and other, non-language areas than were the home videotapes to capture them. In these instances, it was often because the children did not demonstrate early use of the skill on home videotapes, so the coding of loss was not possible, rather than early establishment of a skill and consistent demonstration the behavior. Children with delayed language may utter words too infrequently to be captured predictably on home videotape. We found it important to use all available videotape when expressive language was the focus. It is also important to decide whether the criteria for amount of language before loss should be set at one to two words in addition to mama and dada or five or more words. In the current study, possible loss and definite loss of expressive language were combined for analyses, which may have affected the extent of consistency. The majority of children with ASD vocalized (uttered sounds) in 12-month videotapes and continued to vocalize in subsequent videos. For this domain, no loss was coded because the frequency of vocalizations remained constant; the no loss code was not an artifact of zero frequency in early tapes. Age is also an important factor for the coding of loss. Loss was more often coded for children with videotapes at 12 and 24 months or months than for children with videotapes at months. The birthday and non-birthday context of the videotaping may be consequential for the elicitation of some behaviors more than others. For example, if the child does not display social behaviors at a birthday party, which present many opportunities for social engagement, it may suggest impairment in this domain. Compared to children with ASD, typically developing children demonstrated behaviors at higher frequencies and less often displayed the absence of a behavior. The higher frequencies of most behaviors for typically developing children suggest that home videotapes do provide the opportunity to display behaviors because we were able to capture those behaviors if they were demonstrated regularly. If video codes indicated inconsistent frequencies of behavior for typically developing children, then the validity of the videotape would be challenged. Previous research has found significant positive correspondence between parental report and observer judgment for typical children (e.g., Camaoini et al. 1991; Dale et al. 1989; Ring and Fenson 2000), and moderate to strong concordance for children with autism and other clinical diagnoses (Miller et al. 1995; Faraone 1995). Based on the current study, clinicians may have as much confidence in parental reports of language loss and onset in a sample of children with autism as they can in other clinical samples, but it may be prudent to supplement parental report with

10 J Autism Dev Disord (2008) 38: assessments from other sources for non-language areas. At the very least, parental report is a useful means of identifying children at risk who should then be examined more fully (Shinnar et al. 2001). Limitations of this study include the small sample size of children who had home videotapes from all time points. Larger samples of children with videotapes at key ages are needed to obtain adequate power to pinpoint differences in the distribution of consistency and no consistency to better determine for which group consistency is highest. A larger sample size would also allow for the statistical adjustment for other variables that might influence accuracy of parental report, such as severity of symptoms for children and parent characteristics, such as maternal education. We also caution that the data from parents were gathered retrospectively. Parents judgments about past developmental milestones may depend on their children s current developmental stage and the time interval between the assessments; more discrepancy occurs with increased lapse of time from the event (Majnemer and Rosenblatt 1994). In certain areas, mothers knowledge is informed by their children s more recent rather than past achievements in particular areas (Tamis-LeMonda et al. 1998). Lord and colleagues (2004) found that although parents were quite consistent in their reports of regression over several interviews, there was evidence of some forward telescoping: Parents had the tendency to remember events as occurring closer to the present than originally reported. In conclusion, parental reports of onset and loss of expressive language are consistent with observer codes from home videotapes during the first few years of a child s life. Parents may be considered reliable sources of information about when expressive language began and when words were lost. However, little consistency was found between parent reports of losses in non-language domains and observer coded home videotapes, indicating that parental reports of early non-language behaviors could benefit from information from supplemental sources. Acknowledgments This study was supported by a grant from the National Institute of Child Health and Human Development (NICHD), HD 35458, M.A. Spence, P.I. This project was conducted under the auspices of the Collaborative Programs of Excellence in Autism network. We gratefully acknowledge the contributions made by Kelly Jarvis to the coding of the videotapes and many other aspects of the project. Professor Carol Whalen provided valuable suggestions on an earlier draft of the manuscript. We also thank the children and parents who participated in this study. References Adrien, J. 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