The Pediatric Autism Research Cohort (PARC) Study: protocol for a patient-oriented prospective study examining trajectories of functioning in children with autism.

INTRODUCTION: The developmentally variable nature of autism poses challenges in providing timely services tailored to a child's needs. Despite a recent focus on longitudinal research, priority-setting initiatives with stakeholders highlighted the importance of studying a child's day-to-day functioning and social determinants of health to inform clinical care. To address this, we are conducting a pragmatic multi-site, patient-oriented longitudinal investigation: the Pediatric Autism Research Cohort (PARC) Study. In young children (<7 years of age) newly diagnosed with autism, we will: (1) examine variability in trajectories of adaptive functioning from the point of diagnosis into transition to school; and (2) identify factors associated with trajectories of adaptive functioning. METHODS AND ANALYSIS: We aim to recruit 1300 children under 7 years of age with a recent (within 12 months) diagnosis of autism from seven sites: six in Canada; one in Israel. Participants will be followed prospectively from diagnosis to age 8 years, with assessments at 6-month intervals. Parents/caregivers will complete questionnaires administered via a customized online research portal. Following each assessment timepoint, families will receive a research summary report describing their child's progress on adaptive functioning and related domains. Analysis of the longitudinal data will map trajectories and examine child, family and service characteristics associated with chronogeneity (interindividual and intraindividual heterogeneity over time) and possible trajectory turning points around sensitive periods like the transition to school. ETHICS AND DISSEMINATION: Ethics approvals have been received by all sites. All parents/respondents will provide informed consent when enrolling in the study. Using an integrated knowledge translation approach, where stakeholders are directly engaged in the research process, the PARC Study will identify factors associated with trajectories of functioning in children with autism. Resulting evidence will be shared with government policy makers to inform provincial and national programs. Findings will be disseminated at conferences and published in peer-reviewed journals.

Trajectory research in children with an autism diagnosis: A scoping review.

LAY ABSTRACT: The types of outcomes studied in children on the autism spectrum include clinical characteristics, such as social functioning, communication, language, or autism symptoms. Research that measures these outcomes at multiple timepoints is useful to improve our understanding of what to expect as children develop. In trajectory studies, researchers assess outcomes at three or more timepoints. This method has advantages over two-timepoint studies because it allows researchers to describe changes in the speed of development, such as accelerations, plateaus, or slowdowns. We identified and reviewed 103 published trajectory studies in children (to age 18 years) with an autism diagnosis. Importantly, we did not include studies of treatments or their effects, nor did we summarize the results of studies. Instead, this review summarizes the characteristics of the available published research, including the methods used, the many different outcomes that have been studied over time and the ages over which they have been studied. This summary may be of interest to autistic people and caregivers (parents) who want to know about the existence of research that provides answers about what to expect during an autistic child's development. We have recommended that future trajectory research efforts try to make up for the lack of studies from low- and middle-income countries; that more attention is given to the following outcomes that are meaningful to caregivers and autistic people; and to try to fill in the age gaps where more outcome-specific data are needed.

Protocol for the COVID-19 Wellbeing and Stress Study: a longitudinal study of parent distress, biological stress and child biopsychosocial development during the pandemic and beyond.

INTRODUCTION: The COVID-19 pandemic has had a unique impact on the mental health and well-being of pregnant individuals and parents of young children. However, the impact of COVID-19-related stress during pregnancy on early child biopsychosocial development, remains unclear. The COVID-19 Wellbeing and Stress Study will: (1) investigate the impact of different forms of prenatal stress experienced during the pandemic (including objective hardship, perceived psychological distress and biological stress) on child stress biology, (2) examine the association between child stress biology and child developmental outcomes, (3) determine whether child stress biology acts as a mechanism linking prenatal stress to adverse child developmental outcomes and (4) assess whether gestational age at the onset of the COVID-19 pandemic or child sex, moderate these associations. METHODS AND ANALYSES: The COVID-19 Wellbeing and Stress Study is a prospective longitudinal study, consisting of six time points, spanning from pregnancy to 3 years postpartum. The study began in June 2020, consisting of 304 pregnant people from Ontario, Canada. This multimethod study is composed of questionnaires, biological samples, behavioural observations and developmental assessments ETHICS AND DISSEMINATION: This study was approved by the Hamilton Integrated Research Ethics Board (#11034) and the Mount Saint Vincent University Research Ethics Board (#2020-187, #2021-075, #2022-008). Findings will be disseminated through peer-reviewed presentations and publications, community presentations, and electronic forums (social media, newsletters and website postings).

Predictors of harsh parenting practices and inter-partner conflict during the COVID-19 pandemic in Ontario, Canada: a cross-sectional analysis from the Ontario Parent Survey.

OBJECTIVES: Guided by the bioecological model, the purpose of this study was to examine the associations of (1) individual level factors (sociodemographic, health behaviour and mental health), (2) family (micro) level COVID-19 experiences (difficulty with household management, managing child mood and behaviour, and pandemic-related positive experiences) and (3) community (macro) level factors (residential instability, ethnic concentration, material deprivation and dependency, an indicator of age and labour force) with harsh parenting practices and inter-partner conflict during the early lockdown of the COVID-19 pandemic in Ontario, Canada. DESIGN: A cross-sectional analysis of data from the Ontario Parent Survey. SETTING: A convenience sample of 7451 caregivers living in Ontario, Canada, at the time of baseline data collection (May-June 2020). PARTICIPANTS: Caregivers aged 18 years and older with children 17 years or younger. OUTCOME MEASURES: Parenting practices over the past 2 months was assessed using a published modification of the Parenting Scale. The frequency of inter-partner conflict over the past month was assessed using the Marital Conflict scale. RESULTS: Individual (sociodemographic factors, alcohol use, and higher depressive and anxiety symptoms) and family (difficulties with managing the household and child mood and behaviour) level factors were positively associated with inter-partner conflict and harsh parenting practices. Having fewer positive experiences (eg, performing activities with children), and economic adversity at the family level were positively associated with inter-partner conflict but inversely associated with harsh parenting. At the community level, residential instability was negatively associated with harsh parenting practices. CONCLUSIONS: Individual and family level factors were associated with harsh parenting and inter-partner conflict. The associations of fewer positive experiences and economic hardship with harsh parenting practices may be more complex than initially thought. Efforts that raise awareness and address caregiver mental health concerns are needed as part of the pandemic response to promote positive inter-partner and parent-child interactions.

Assessing the combined effect of household cooking fuel and urbanicity on acute respiratory symptoms among under-five years in sub-Saharan Africa.

Background: This study sought to investigate the association between urbanicity (rural-urban residency), the use of solid biomass cooking fuels and the risk of Acute Respiratory Infections (ARIs) among children under the age of 5 in sub-Saharan Africa (SSA). Methods: Cross-sectional data from the most recent surveys of the Demographic and Health Survey Program conducted in 31 sub-Saharan African countries were pooled for the analysis. The outcome variables, cough and rapid short breath were derived from questions that asked mothers if their children under the age of 5 suffered from cough and short rapid breath in the past two weeks preceding the survey. To examine the associations, multivariable negative log-log regression models were fitted for each outcome variable. Results: Higher odds ratios of cough occurred among children in urban households that use unclean cooking fuel (aOR = 1.05 95% CI = 1.01, 1.08). However, lower odds ratios were observed for rural children in homes that use clean cooking fuel (aOR = 0.93 95% CI = 0.87, 0.99) relative to children in urban homes using clean cooking fuel. We also found higher odds ratios of short rapid breaths among children in rural households that use unclean cooking fuel compared with urban residents using clean cooking fuel (aOR = 1.12 95% CI = 1.08, 1.17). Conclusion: Urbanicity and the use of solid biomass fuel for cooking were associated with an increased risk of symptoms of ARIs among children under five years in SSA. Thus, policymakers and stakeholders need to design and implement strategies that minimize children's exposure to pollutants from solid biomass cooking fuel. Such interventions could reduce the burden of respiratory illnesses in SSA and contribute to the realization of Sustainable Development Goal 3.9, which aims at reducing the number of diseases and deaths attributable to hazardous chemicals and pollution of air, water and soil.

Joint effect of water and sanitation practices on childhood diarrhoea in sub-Saharan Africa.

BACKGROUND: Diarrhoea remains the major cause of morbidity and mortality of children under five years in Africa. Several studies have shown that inadequate and unsafe water, lack of sanitation, and poor hygiene practices are complex issues for different pathogens and accountable for the occurrence of diarrhoea diseases. We assessed the combined effect of household's source of drinking water and type of toilet facility and residential wellbeing on the incidence of childhood diarrhoea in 33 Sub-Saharan Africa countries while accounting for relevant compositional and contextual factors. METHODS: The 2010-2019 datasets from the Demographic and Health Surveys were drawn for analyses. The outcome variable used in this study was the incidence of childhood diarrhoea. Three negative log-log generalized linear regression models were then sequentially fitted to the data to examine the joint effect of household water and sanitation practices on child diarrhoea. The results were presented using crude odds ratios (CORs) and adjusted odds ratios (AORs) at 95% confidence intervals (CIs). Using ArcGIS software, maps were design to unveil the spatial distribution of key variables. FINDINGS: Approximately 16% of the 307,741 mothers interviewed reported an incidence of diarrhoea disease among children under-five years in their households. The results showed that a household depending on an unimproved source of drinking water and with an unimproved type of toilet facility was not significantly associated with childhood diarrhoea. However, those with improved drinking water but an unimproved type of toilet facility had higher odds of reporting childhood diarrhoea (AOR = 1.020, 95% CI = 1.003-1-036) compared to those in households with both improved source of drinking water and type of toilet facility. Across the geographical regions, Eastern (aOR = 1.102, 95% CI = 1.084-1.120) and Central Africa (aOR = 1.102, 95% CI = 1.083-1.121) were more likely to experience child diarrhoea. CONCLUSION: Water and sanitation practices such as the source of drinking water and toilet facility, and geographic region had significant effects on childhood diarrhoea in sub-Saharan Africax. The findings suggest the need for multi-sectoral actions that recognise the geo-spatial and temporal characteristics identified in the study through regional to national policies. Water and sanitation community-based interventions that seek to improve equitable access to safe water and sanitation in the sub-region should be intensified.

Variable patterns of daily activity participation across settings in autistic youth: A latent profile transition analysis.

LAY ABSTRACT: What people do or engage in in their daily lives, or daily life participation, is often linked to their state of being happy and healthy, as well as potential for living independently. To date, little research has been conducted on daily activity participation by autistic youth at home, at school or in the community. Learning more about individual differences in participation levels and what might influence them can help to create custom supports for autistic youth and their families. In this study, 158 caregivers of autistic youth were asked how often their children took part in 25 common activities at two assessments, about one year apart. The analysis showed three profiles for each of the home and school settings and two profiles for the community setting. These profiles reflected distinct patterns in how often autistic youth took part in various daily activities, particularly in doing homework, school club activities and community gatherings. Most autistic youth were in profiles marked by often taking part at home but less often at school and in the community, and about three-fourths of them tended to stay in the same profile over time. Autistic youth with limited participation profiles were more likely to have lower scores on measures of cognitive ability and daily life skills and more challenging behaviour, and faced more barriers in their environment. These findings show how important it is to think about each autistic person's strengths and weaknesses, and changing needs, to better support their daily life participation.

Longitudinal associations between early childhood irritability and adolescent depression symptoms in autistic children are mediated by peer relationships but not educational engagement.

In the general population, irritability is associated with later depression. Despite irritability being more prevalent in autistic children, the long-term sequelae are not well explored. We tested whether irritability in early childhood predicted depression symptoms in autistic adolescents, and whether associations could be explained by difficulties in peer relationships and lower educational engagement. Analyses tested the longitudinal associations between early childhood irritability (ages 3-5) and adolescent depression symptoms (age 14) in a prospective inception cohort of autistic children (N = 390), followed from early in development shortly after they received a clinical diagnosis. Mediators were measured in mid-childhood (age 10) by a combination of measures, from which latent factors for peer relationships and educational engagement were estimated. Results showed early childhood irritability was positively associated with adolescent depression symptoms, and this association remained when adjusting for baseline depression. A significant indirect pathway through peer relationships was found, which accounted for around 13% of the association between early childhood irritability and adolescent depression, suggesting peer problems may partially mediate the association between irritability and later depression. No mediation effects were found for education engagement. Results highlight the importance of early screening and intervention for co-occurring irritability and peer problems in young autistic children.

Social Disparities in Mental Health Service Use Among Children and Youth in Ontario: Evidence From a General, Population-Based Survey.

OBJECTIVES: To examine differences in mental health-related service contacts between immigrant, refugee, racial and ethnic minoritized children and youth, and the extent to which social, and economic characteristics account for group differences. METHODS: The sample for analyses includes 10,441 children and youth aged 4-17 years participating in the 2014 Ontario Child Health Study. The primary caregiver completed assessments of their child's mental health symptoms, perceptions of need for professional help, mental health-related service contacts, experiences of discrimination and sociodemographic and economic characteristics. RESULTS: Adjusting for mental health symptoms and perceptions of need for professional help, children and youth from immigrant, refugee and racial and ethnic minoritized backgrounds were less likely to have mental health-related service contacts (adjusted odds ratios ranged from 0.54 to 0.79), compared to their non-immigrant peers and those who identified as White. Group differences generally remained the same or widened after adjusting for social and economic characteristics. Large differences in levels of perceived need were evident across non-migrant and migrant children and youth. CONCLUSION: Lower estimates of mental health-related service contacts among immigrant, refugee and racial and ethnic minoritized children and youth underscore the importance and urgency of addressing barriers to recognition and treatment of mental ill-health among children and youth from minoritized backgrounds.

The Influence of Bilingual Language Exposure on the Narrative, Social and Pragmatic Abilities of School-Aged Children on the Autism Spectrum.

We examined the narrative abilities of bilingual and monolingual children on the autism spectrum (AS), whether bilinguals presented stronger social and pragmatic language abilities compared to monolinguals, and the link between narrative, social, and pragmatic language abilities.The narrative, social, and pragmatic language skills of school-aged bilinguals (n = 54) and monolinguals (n = 80) on the AS were assessed using normed measures. Language exposure was estimated through a parent questionnaire.Bilinguals performed similarly to monolinguals on measures of narrative, social, and pragmatic language skills. However, balanced bilinguals performed better on a nonliteral language task.Overall, results indicate that bilingual children on the AS can become as proficient in using language as monolinguals and may enjoy a bilingual advantage.

Disentangling global and domain-level adaptive behavior trajectories among children with autism spectrum disorder.

BACKGROUND: Heterogeneity in adaptive behavior abilities among people with autism spectrum disorder (ASD) is expressed not only as uneven levels of impairment across domains, but also in the developmental trajectories of adaptive skills. We studied the question of whether, after accounting for global adaptive behavior development, we find evidence of heterogeneity in the trajectories of specific domains of adaptive behavior. METHODS: A sample of 504 children with ASD was obtained by combining data from two independent natural history studies conducted in North America. We used a factor of curves model to explain growth between 36 and 138 months in Vineland Adaptive Behavior Scales, Second Edition (VABS) age equivalents as a function of domain-specific and global growth processes. RESULTS: The domain-specific trajectories in all three domains (Communication, Daily Living Skills, and Socialization) reflected impairment relative to age expectations as well as slower-than-expected growth with age, and the parameters of these trajectories were moderately-to-strongly correlated across domains. The global adaptive behavior trajectory had an initial (36-41 months of age) developmental level of about 22 age-equivalent months, and eventually slowed after initially increasing by about 6 months each year. The global trajectory accounted for the majority of variance in the domain-level processes; however, additional variance remained (14%-38%) in the domain-level intercepts, slopes, and quadratic processes. CONCLUSIONS: These results extend existing theoretical and empirical support for the hierarchical structure of adaptive behavior to include its development over time in clinical samples of children with ASD. A latent global trajectory may be sufficient to describe the growth of adaptive behavior in children with ASD; however, the remaining domain-specific variability after accounting for global adaptive behavior development allows for the possibility that differential effects of intervention on specific domains may be possible and detectable.

Continuity of trajectories of autism symptom severity from infancy to childhood.

BACKGROUND: Behavioral symptom trajectories are informative of the development of young children at increased likelihood for autism spectrum disorder (ASD). METHODS: Developmental trajectories of early signs were examined in a cohort of siblings of children diagnosed with ASD (n = 502) from 6 to 18 months using the Autism Observation Scale for Infants (AOSI), and from 18 months to 5-7 years using the Autism Diagnostic Observation Schedule (ADOS). Diagnostic outcomes for ASD at age 3 confirmed diagnosis for 137 children. We further analyzed the conditional probability of a switch from a trajectory measured with the AOSI to a trajectory measured with the ADOS as well as predictors from age 6 months. RESULTS: We derived three early trajectories of behavioral signs ("Low," "Intermediate," and "Increasing") from 6 to 18 months using the AOSI. We then derived three similar, distinct trajectories for the evolution of symptom severity between 18 and 60-84 months of age (Low, Intermediate, Increasing) using the ADOS. Globally, the Low trajectory included children showing fewer ASD signs or symptoms and the Increasing trajectory included children showing more severe symptoms. We also found that most children in the Low AOSI trajectory stayed in the corresponding ADOS trajectory, whereas children in an Increasing AOSI trajectory tended to transition to an Intermediate or Increasing ADOS trajectory. Developmental measures taken at 6 months (early signs of ASD, Fine Motor, and Visual Reception skills) were predictive of trajectory membership. CONCLUSIONS: Results confirm substantial heterogeneity in the early emergence of ASD signs in children at increased likelihood for ASD. Moreover, we showed that the way those early behavioral signs emerge in infants is predictive of later symptomatology. Results yield clear clinical implications, supporting the need to repeatedly assess infants at increased likelihood for ASD as this can be highly indicative of their later development and behavior.

Measuring the association between behavioural services and outcomes in young children with autism spectrum disorder.

BACKGROUND: Children with autism spectrum disorder (ASD) receive a wide range of services. AIMS: To examine the association between behavioural services received by children with ASD between ages 2 and 5 years and outcomes during primary school years. METHODS: A total of 414 preschool-aged children diagnosed with ASD were enrolled at five Canadian sites and were assessed within four months of diagnosis (T1), six months later (T2), 12 months later (T3), at school entry (T4), and then annually (T5-T8) to 11 years of age. The association between the receipt of behavioural services during T1 to T3 and T8 outcomes related to adaptive behaviour and behavioural problems was modelled using linear regressions adjusted for immigrant status, family income, child's age at diagnosis, site, sex assigned at birth, and baseline (T1) outcome. RESULTS: Children who received behavioural services during at least one time period from T1 to T3 did not have significantly different outcomes at T8 than children who did not receive any behavioural services. IMPLICATIONS: Pre-school use of behavioural services was not found to affect outcomes during later childhood. Numerous challenges accompany studies of the association between pre-school service use and later outcomes in a heterogeneous ASD sample. Recommendations for study design are provided.

Developmental cascades between insistence on sameness behaviour and anxiety symptoms in autism spectrum disorder.

Autistic children experience high rates of anxiety. Insistence on sameness behaviour (IS) is a core feature of autism that appears correlated with anxiety severity. The objective of this study was to examine the longitudinal relations between anxiety and IS in autistic children using a developmental cascade model. A longitudinal cohort of 421 autistic children was followed between 4 and 11 years of age. Anxiety was quantified using items from the Anxiety Problems subscale of the Child Behavior Checklist; sameness behaviours were measured using the Repetitive Behavior Scale-Revised, Ritualistic/sameness subscale (both parent-report measures). Structural equation modelling was used to examine the longitudinal and directional associations between anxiety and IS at four time-points, through cross-lagged panel models (CLPM) with and without a random-intercepts component (RI-CLPM). Both the CLPM and the RI-CLPM had good fit. Significant directional associations were detected whereby elevated or increasing IS preceded elevated or increasing anxiety symptoms 1-2 years later, respectively. Stable baseline tendencies towards anxiety and IS as between-person traits (intercepts) were strongly associated (standardized estimate = 0.69, p < 0.001). The magnitude of the cross-sectional associations between anxiety and IS appeared to lessen with age. IS and anxiety symptoms in autism are closely related. They appear to be shared traits that mirror each other particularly in younger children. Increasing IS may be a sign of emerging future anxiety. Interventions that target IS to reduce or prevent anxiety amongst school-aged autistic children merit further study.

Body Weight at Age Four Years and Readiness to Start School: A Prospective Cohort Study.

Background: Adolescents with obesity have lower academic performance, but little is known about the association between body weight in early childhood and school readiness. The objective was to examine the association between age- and sex-standardized body mass index (zBMI) and body weight status and school readiness in young children. Methods: A prospective cohort study in Toronto, Canada, was conducted in young children enrolled in TARGet Kids!. Children's weight and height were measured before the start of kindergarten. Children's school readiness was measured by the Early Development Instrument (EDI), a validated teacher-completed instrument that assesses children's skills and behaviors in five developmental domains in kindergarten. Generalized estimating equations, adjusted for relevant confounders, were used in the analysis. Results: The study included 1015 children (1217 observations): 52% were male and mean age at zBMI was 4.2 years [50 months (SD 12.1)] and school readiness was 5.2 years [62.7 months (SD 6.9)]. There was no evidence found that zBMI was associated with school readiness. However, in a post hoc analysis, being classified as overweight or with obesity in kindergarten was associated with twofold higher odds of vulnerability in school readiness and a lower social competence score compared with their normal weight peers. Conclusions: Being classified as overweight or with obesity was associated with poor school readiness in year 2 of kindergarten. Early interventions to promote healthy growth before school entry may help promote development and school readiness in young children. www.clinicaltrials.gov (NCT01869530).

Construct Validity of the Autism Classification System of Functioning: Social Communication (ACSF:SC) Across Childhood and Adolescence.

This study examined the construct validity of the Autism Classification System of Functioning: Social Communication (ACSF). Participants included 145 parents of children with autism (2-19 years). The degree of convergent and discriminant validity between parent reported ACSF and subscales from Social Responsiveness Scale 2nd edition and Behavior Assessment System for Children, 3rd Edition were examined against a priori hypotheses. We examined construct validity in the entire sample as well as in specific age cohorts. Our findings suggest that ACSF can provide a valid classification system of social communication ability in children with autism 2-19 years of age, and its two subscales may be used to examine different aspects of social communication ability.

Population-Based Teacher-Rated Assessment of Anxiety Among Canadian Kindergarten Children.

Despite anxiety being a prevalent mental health problem in children, little data exist on the pervasiveness and levels of anxiety symptoms in kindergarteners. Data from the Early Development Instrument, a teacher-completed, population-level measure of child development, were collected across Canada from 2004 to 2015. The final analytic sample consisted of 974,319 children of whom 2.6% were classified as "highly anxious". Compared to children who exhibited "few to none" anxious behaviors, highly anxious children were more likely to be male, have English/French as a second language, and have a special needs designation. Furthermore, compared with their less anxious peers, highly anxious children had between 3.5 and 6.1 higher odds of scoring below the 10th percentile cut-off in physical, social, language/cognitive and communication domains. Our findings suggest that anxious behaviors are related to children's overall health and illustrate the consistency and extensiveness of anxiety at a very young age among Canadian children.

Examining clinical characteristics of autism and links with parent perceptions of sibling relationship quality.

LAY ABSTRACT: Sibling relationship quality is important for the well-being of children on the autism spectrum and their siblings. Little is known, however, about how varied behavior and abilities of children on the autism spectrum may be associated with parent perceptions of domains of sibling relationship quality. We drew data from a subsample of 119 children on the autism spectrum (ages 10-11 years), participating in an ongoing longitudinal study. We looked at how three clinical characteristics (autism symptoms, behavioral difficulties, and communication ability) related to four areas of parent-reported sibling relationship quality (warmth/closeness, conflict, relative status/power, and rivalry). We also examined whether the strength of the association between behavioral difficulties and parent-reported sibling relationship quality was influenced by communication ability. We found that more severe autism symptoms were associated with less conflict and rivalry, and higher communication ability was associated with more relative status/power. We also found that children on the autism spectrum with more behavioral difficulties and weaker communication ability had less warmth/closeness in their sibling relationships. Our findings highlight that it is important to consider autism symptoms, behavioral difficulties, and communication ability, as well as multiple domains of relationship quality, to better understand how parents view the relationships between autistic children and their siblings. Clinically, methods for improving sibling relationships may include teaching conflict resolution strategies to children on the autism spectrum with stronger communication abilities and their siblings, and fostering sibling connection for those with lower communication abilities.

Predictive Validity of the Infant Toddler Checklist in Primary Care at the 18-month Visit and School Readiness at 4 to 6 Years.

OBJECTIVE: The American Academy of Pediatrics recommends developmental surveillance and screening in early childhood in primary care. The 18-month visit may be an ideal time for identification of children with delays in language and communication, or symptoms of autism spectrum disorder (ASD). Little is known about the predictive validity of developmental screening tools administered at 18 months. Our objective was to examine the predictive validity of the Infant Toddler Checklist (ITC) at the 18-month health supervision visit, using school readiness at kindergarten age as the criterion measure. METHODS: We designed a prospective cohort study, recruiting in primary care in Toronto, Canada. Parents completed the ITC at the 18-month visit. Teachers completed the Early Development Instrument (EDI) when the children were in Kindergarten, age 4-6 years. We calculated screening test properties with 95% confidence intervals (CIs). We used multivariable logistic and linear regression analyses adjusted for important covariates. RESULTS: Of 293 children (mean age 18 months), 30 (10.2%) had a positive ITC including: concern for speech delay (n = 11, 3.8%), concern for other communication delay (n = 13, 4.4%), and concern for both (n = 6, 2.0%). At follow-up (mean age 5 years), 54 (18.4%) had overall EDI vulnerability, 19 (6.5%) had vulnerability on the 2 EDI communication domains. The ITC sensitivity ranged from 11% to 32%, specificity from 91% to 96%, false positive rates from 4% to 9%, PPV from 16% to 35%, NPV from 83% to 95%. A positive ITC screen and ITC concern for speech delay were associated with lower scores in EDI communication skills and general knowledge (ß = -1.08; 95% CI: -2.10, -0.17; ß = -2.35; 95% CI: -3.63, -1.32) and EDI language and cognitive development (ß = -0.62; 95% CI: -1.25, -0.18; ß = -1.22; 95% CI: -2.11, -0.58). CONCLUSIONS: The ITC demonstrated high specificity suggesting that most children with a negative ITC screen will demonstrate school readiness at 4-6 years, and low false positive rates, minimizing over-diagnosis. The ITC had low sensitivity highlighting the importance of ongoing developmental surveillance and screening.