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Infant‐Toddler Checklist identifies 18‐month‐old children with communication difficulties in the Swedish child healthcare setting

Abstract Aim At present, there is no reliable method to screen for communication difficulties at age 18‐months in the Swedish child health care. This study examined the psychometric properties of the Communication and Symbolic Behavior Scales Developmental Profile Infant‐Toddler Checklist (ITC) when used at the 18‐month visit in the child healthcare setting. Methods Children aged 16–20 months (n = 679) were screened. Children were referred for an assessment if they screened positive screen or if the parent or nurse was concerned about the child's communicative development. Two groups of positive screens were used in the analysis (n = 78 children), one based on the ITC result, and one combining the ITC with contradicting information from the nurses' informal clinical assessment. Results The AUC ranged from 0.68 to 0.84. The sensitivity was 0.85, and the specificity was 0.59. When the ITC result was combined with the nurses' information, sensitivity increased to 0.88 and specificity to 0.63. The internal consistency was moderate to high, and fit indices were satisfactory. Conclusion The results suggest that the ITC can be used to identify children in need of interventions to enhance communication at 18 months of age, especially in combination with the nurse's assessment.

disorder. 3 Communication and language disorders are also related to problems in adulthood, such as difficulties in peer-relationships, low academic achievement, poor mental health and unemployment. 4 Language disorders have been described as a public health problem. 5 Given that interventions initiated before a child's third birthday have shown to significantly improve their child's development, communication and language, there is a need for methods to reliably identify children with such difficulties at an early age. 6 The public-funded Swedish child health services reach 99% of children aged 0-5. 7 The service is staffed by specialist nurses and general practitioners who offer regular child health visits according to a national child health programme. An increasing focus has been placed on establishing evidence-based methods within the child health services to offer high-quality care and assist the personnel in their busy clinical practice. 8 The need for instruments with favourable psychometric properties to accurately identify children with communication and language difficulties has been highlighted.
However, few methods have been developed and tested in clinical settings. 9 At present, communication and language abilities at 18-months of age are assessed by asking the parents if the child speaks at least 8-10 words and understands more than 8-10 words, a method with low sensitivity. 10 Many nurses report that they informally observe the child's communication and language use, and add their prior knowledge about the child and the family to their assessment. Nationally, the earliest formal screening to identify communication and language difficulties is performed at the health visit at two-and-a-half to three years of age. 11 Screening materials provide an opportunity for healthcare professionals to engage with parents who need more support in promoting their child's development or have misconceptions about typical child development. 12 Screening should be repeated at different ages and should be combined with the healthcare provider's prior knowledge about the child and the family. 13 Numerous methods are available to screen for developmental difficulties, some of which are broadband screens, while others are disorder-specific. 14 It has been proposed that broadband screening methods may be easier to implement as they identify a wider spectrum of disorders that warrant interventions. 14 The Communication and Symbolic Behavior Scales Developmental Profile (CSBS-DP), is a broadband evaluation tool used to identify children with language, communication or developmental disorders.
The CSBS-DP has been studied globally and has shown to be widely applicable with minor cultural adaptations. 15,16 The CSBS-DP consists of three parts, the Infant-Toddler Checklist (ITC), a four-page follow-up Caregiver Questionnaire and the Behavior Sample (BS) assessment. 17 The ITC is a parent questionnaire designed for children aged 6-24 months and consists of a 24-item measure in the three composites social, speech, and symbolic and a single question regarding parental concerns. 17 The psychometric properties in North American studies vary with the age of the child, with a sensitivity of 0.89-0.94 and a specificity of 0.59-0.89. 18 A study of 24-month-old children showed moderate sensitivity and good specificity for the Finnish version of the ITC. 19 Internal consistency is high, with alpha coefficients ranging from 0.86 to 0.92. 18 The ITC has been described as a valuable improvement in clinical practice. 20 Nurses described that parents' understanding of their child's communication increased after filling out the ITC, and nurses were able to alleviate unfounded or excessive worry through its use. 21 The BS is a standardised and norm-referenced assessment using a systematic naturalistic sampling procedure to encourage spontaneous social communication. 17 The BS consists of twenty items that are summed to form social, speech and symbolic composites corresponding to the ITC and has good psychometrics and is valid for evaluating communication development. 22

| Aims
This study aimed to investigate the psychometric properties, including sensitivity and specificity, internal consistency and factor structure of the ITC when used at the 18-month health visit in the Swedish child health service setting to identify children with communication difficulties.

| Setting
The Swedish version of the ITC, translated within the Early Autism Sweden project, 23 was implemented at 10 child health centres in Uppsala and Knivsta municipalities, Sweden which have populations of 215 762 and 17 533, respectively. This version of the ITC has not previously been validated in Sweden. The centres were chosen to represent diverse areas with respect to socio-demographic background as well as the size and urban or rural location of the child health centre.

| Participants
In total, 704 children were screened with the ITC (Figure 1). Age was adjusted for prematurity for children born at or before 36 weeks.
Children younger than 16 months or older than 20 months when  (Table 1).

| Procedure
The ITC was collected at the 18-month child health visit along with a questionnaire regarding social and economic conditions as previously described. 24 The ITC was sent to the families by mail prior to the visit. During the visit, the nurse reviewed the ITC form and scored the screen as positive or negative based on American norms. As described in the official CSBS-DP manual, children who screened positive only on the speech composite were rescreened at the age of 21 months and seen as positive after two consecutive positive screenings. 17 The nurses were instructed to refer children to a speech and language pathologist for further assessment if the screen was positive or if the parent or nurse was concerned about the child's communicative development, regardless of the ITC result.
The nurses were instructed to note when their informal assessment contradicted the ITC result or when the referral was based on parental concerns. Two groups of positive screens were used in the analysis, one based on the ITC result, and one combining the ITC with contradicting information from the nurses' informal clinical assessment including parental concerns, in which case the latter was given precedence.
The 44 children who were referred were offered a speech and language pathologist assessment using the BS in the child's home environment. Randomly selected children with a negative screen (n = 34) were assessed in the same way.  Could not be reached n = 1 The BS assessments were scored according to the CSBS-DP manual producing raw and standardised scores for the total score as well as the social, speech and symbolic composites. The North American cut-off values for the BS were used to indicate a positive or negative assessment. 17 Video recordings of 19 of the 78 BS assessments were scored independently by two experienced speech and language pathologists. The inter-rater reliability ranged from 0.721 to 0.928, for the social, speech and symbolic composites, with speech giving the lowest reliability.

| Data analysis
Data analysis was performed using SPSS version 23 (IBM Corp.) and R version 3.5.2 (R Core Team). Means, ranges, frequencies and proportions were used to describe the sample. Sensitivity, specificity and area under the receiver operating curve (AUC) values were computed to explore concurrent validity. 25 The sensitivity and specificity analyses were performed using both the North Among the children with a positive ITC screen, differences between those who were referred for further assessment and those who were not referred were analysed using the t-test for the ITC scores and chi-square for parental demographic factors. Inter-rater reliability of the BS was calculated using generalisability coefficients. 15 The g coefficient can range between zero and one, where higher values indicate stronger reliability.

| Missing data
The ITC data were missing for 20 of 24 variables, 0.10 of the cases and 0.56 of the values. The variables with most missing data were those regarding how many blocks the child stacks and if the child puts two words together, with 0.02 missing data in both cases.
Multiple imputations were performed, after which the three composite scores and the total score were calculated.  the video recordings and the worksheet, the child was excluded from the analysis (n = 3).
In total, 40 iterations were run in the multiple imputation. boys and 69 girls) scored at the level of concern for social, symbolic, speech (two consecutive positive screenings) or total score (Table 3) based on Swedish cut-off values. Most of these children screened positive for one composite, most often symbolic (n = 124, 18.26%).

| RE SULTS
Only 25 children (3.68%) scored at the level of concern for all three composites and total score (Table 3).
Of the positive screened children, 129 were not referred, three declined assessment and one family could not be reached. There were no differences between the 48 children who were referred, and the 129 children who were not referred regarding parental demographic factors (p = >0.05). There were significant differences between the groups with respect to the ITC scores (p-value ranging from 0.005 to ≤0.000). The referred children scored lower than the non-referred children on all composites and total score.

| Behaviour sample
In total, 78, children were assessed between 17 and 23 months of Of the assessed children, 27 (21 boys, six girls) had communication difficulties based on the BS assessment. The AUC ranged between 0.68 and 0.84 (Table 4.) The results indicate a sensitivity of 0.85 and a specificity of 0.59 for the ITC alone based on the Swedish cut-off levels. When combining the ITC with contradicting information from the nurses' informal clinical assessment, sensitivity increased to 0.88 and specificity to 0.63. Using the North American norms yielded a lower sensitivity (0.79) but a higher specificity (0.72) ( Table 5).

| Internal consistency and factor structure
Analyses of all three subscales and total scores indicated that internal consistency was good for social (α = 0.84) and total (α = 0.87), and somewhat lower for speech (α = 0.66) and symbolic (α = 0.70).
All fit indices for the three-factor model were satisfactory, suggesting acceptable fit (Comparative fit index = 0.93; Tucker-Lewis Index = 0.92; Root mean square error of approximatio n = 0.04).

| D ISCUSS I ON
The study aimed to investigate the psychometric properties of the ITC when applied in the Swedish child health services for children aged 18 months to identify children with communication difficulties.
Although the sensitivity of the instrument alone was relatively high (0.85) for those children who were referred for speech and language pathologist assessment, the specificity was moderate (0.59). The sensitivity was somewhat lower than previous studies, 18 although a Finnish study with two-year-old children reported a lower sensitivity. 19 This difference in sensitivity might be explained by differences in the age of the children screened and the instrument used to assess the children. Concurrent validity in the present study was based on comparison to the result of the BS, which assessed the same behaviours as those screened for in the ITC, while the Finnish study used The Reynell Developmental Language Scales III, which measures slightly different skills. 19 The AUC values of 0.68-0.84 indicate that accuracy was good for the social and symbolic composites and total score but poor for the speech composite, as AUC values below 0.7 are often considered as poor discrimination and AUC values over 0.8 as good discrimination. 28 Both accuracy and inter-reliability were low for speech, which was in line with previous research. 16 One reason for this finding may be that it is often difficult to Some of the children who were false-negative on the ITC alone were referred due to concerns mentioned by the parents or that arose during the nurse's assessment. When this contradicting information was given precedence regarding discrepancies between the ITC results and the nurses' informal assessment in the clinical encounter, sensitivity and specificity increased to 0.88 and 0.63, respectively.
The sensitivity of the ITC is substantially higher than the method used at the 18-month health visit nationally, which has a sensitivity of 0.32. 10 The specificity of the ITC was lower than current stan- The results indicated adequate internal consistency of the ITC total score and subscales, and our factor analysis confirmed the original factor structure. One previous study reported having conducted a confirmatory factor analysis of the three ITC subscales. 16 The sample consisted of 12-month-old children, and some items concerning verbal abilities were omitted from their analysis. As chisquare was the only fit measure reported in that study, we could not compare their results to our own. This measure is problematic, as it provides a dichotomous answer and a large sample size increases the risk of type I errors. 29 The measures used to assess the model fit in the current study yield a better estimation of fit.

| Strengths and limitations
This is the first study to explore the psychometric properties of the ITC in the Swedish child health service and adds to the knowledge base regarding early identification of children with communication difficulties. Missing data for the ITC and the BS were handled with multiple imputation, which is superior to many other imputation techniques. Not all children with a positive screen were referred and were therefore not assessed. It was therefore not possible to investigate the predictive capacities of the method. The concurrent validity was based on the result of the BS. Further knowledge about concurrent validity and predictive capacities could be gained from analysis of results from the language screen performed at two-and-a-half to three years of age and further visits to a SLP or psychologist. In future research, it would be of importance to investigate the gender differences seen in the present analysis, as more boys than girls had a positive screening result. A difference between socio-economic groups in identification has been shown in previous studies. 30 An analysis of socio-economic differences in the concurrent validity of the ITC would therefore be of importance in future research.

| CON CLUS IONS
The ITC identified children with communication and language difficulties with good sensitivity and acceptable specificity, especially when the ITC was combined with the nurses' developmental surveillance and prior knowledge of the child and family. This suggests that the ITC can be used to identify children in need of communication interventions at 18 months of age. The ITC appeared to yield reliable results with adequate internal consistency and factor structure in the Swedish setting.